Introduction: How I Hypermiled My Car.

Picture of How I Hypermiled My Car.

When it comes to my vehicle, I dont care about performance power output. I want a safe and comfortable ride however I want my car to use the least amount of fuel to get me to my destinations.

I'm a one car kind of guy and I don't care about its looks, I aim to own her as long as I can. For folks who have that itch to get a replacement vehicle every 3 years or so then this instructable may not make much sense. For those privileged few of us who keep our cars long term (I mean LONG years!) then this instructable may have some ideas you can use.

Hypermiling (or I guess hyperkilometering depending what unit you prefer) is a bunch of techniques involving driving habits and vehicle modifications to get the maximum fuel economy out of a vehicle. Note that basic periodic maintenance is a given such as regular oil changes, having steering aligned, using fully synthetic oils, proper weight oil for the vehicle, recommended tire pressures, good tires, clean filters and fuel etc.

Some folks do some pretty extreme mods to their vehicles or use unsafe driving habits. This instructable is NOT about that (for example that thing in the second pic). My family and neighbours already call me a mad scientist and macguyver but I certainly don't want another nickname by driving around a car looking like that!

All the tips I have outlined in this publication works for me in terms of fuel economy and safety. I have tried various techniques over the years and I have settled on those I have explained below. These may not work for you! I have simply presented what works for my vehicle and I'm extremely happy with the results.

Here is how I made my car's range on a full tank extend from below 300km to approximately 530km. My car currently gives me 16.21 km per litre of gasoline. Note that all my mods and changes are fully within the legislative requirements of my region and does not violate the safety devices onboard my car. These first hand practices of mine do NOT compromise my or other drivers' safety on our nation's roads.

Step 1: Driving Style.

Picture of Driving Style.

Gentle acceleration and deceleration goes a long way in terms or wear/tear and fuel economy. My car has automatic transmission but I have read that manual transmissions can offer improved fuel economy.

Each car has its own optimum driving speed for lowest fuel consumption. For my 1999 civic its approximately 80km/hr (which coincidentally is our speed limit here on the highways).

Driving as part of a chain (without riding a person's rear bumper!) is great for reducing air resistance (except for the leader). Remember those documentaries with lobsters migrating? Those delicious crustaceans already knew this energy saving technique.

Coasting downhill (while in drive for automatic transmission vehicles) and also to a stop before applying brakes will contribute to better fuel economy. It has alot to do with predicting the route and driving defensively.

A good example is when I drive my car I get on average 460km but if my wife drives it we are lucky to get 390km. It's all about driving style.

Step 2: Putting in New Fuel Injectors.

Picture of Putting in New Fuel Injectors.

I recently replaced the aged 16 year old injectors in my car and the result was immediate. Smoother, quieter engine. The fuel economy increased significantly. Manufacturers don't ever specify a replacement period for fuel injectors however these critical devices directly affect your drivability and fuel consumption.

In my case, the OEM injectors were heavily congested with deposits and at a price of 46USD per injector, to me that is a great price to get the engine happy again. Due to the age of my 1999 car, I intend to replace the injectors in the next 5 years. For you, depending on the age of your vehicle and behavior of the engine, you can vary your replacement interval.

I'm extremely happy with the replacement DIY job which took my only 1 hour at home. Here is the instructable:

Step 3: Replacing Aged Sensors That Affect Your Fuel Economy.

Picture of Replacing Aged Sensors That Affect Your Fuel Economy.

There are sensors in a fuel injected car that directly affect its fuel consumption. Some can last the lifespan of the car and others have a shorter lifespan. Here is a list of sensors I replaced on my engine.

1. Manifold Absolute Pressure (MAP) Sensor: this basically tells the engine controller how much load the engine is under. Although its pure electronic, with heat and airbourne contaminants, it will fail. I recently changed my MAP sensor and the effect was immediate. Here's the instructable I made for that:

2. Throttle position sensors are mechanical in nature and wear with time. Its possible that the reading at idle is higher that OEM requirements. I replaced mine and although there was no noticeable change to my fuel economy, the car accelerated smoother. Here's the instructable:

3. Replacing your Heated Oxygen Sensors (H2OS) is a great idea. If you didn't know this fact then now you know: Most Fuel additives do poison your H2OS! Everytime you put a fuel cleaner or certain other additives, the H2OS becomes sluggish or simply doesnt respond anymore. I have long since stopped using any sort of additive. My water induction setup actually keeps the internals of my engine clean. Even though these sensors can provide good service for 100,000 miles, in reality it will be far less. I prefer to change my H2OS every 4 years to keep a healthy signal into the engine controller. They cost approximately 30USD but I change mines on my own and to me the cost is worth it in fuel savings. Here is the instructable I did for my car:

Step 4: Reducing Electrical Loads.

Picture of Reducing Electrical Loads.

The less amps the alternator has to supply means it will last a bit longer and less energy is needed to turn it. I basically replaced ALL my car's lights with LEDs. Main headlights, park, rear, cabin, instrument cluster lights etc are all using less power than (urghh vomit) incandescent bulbs.

Using a solar battery maintainer keeps the battery ready for the next start provided you park in sunlight. A 5 Watt panel is a good rating to get energy into the battery.

Step 5: Do NOT Oversize Tire Width.

Picture of Do NOT Oversize Tire Width.

Narrower tires offers less weight, rolling resistance and wind resistance. I'm not talking about putting bicycle thin tires on your car. Too narrow tires will result in vehicle handling plus braking capability being compromised!

For example I used 205s on my car but switched to 185s. The car has a much longer coasting roll when I release the gas pedal with the 185s. Strange enough the OEM tires when I first bought the car were 185s. Go figure.

Step 6: Using a Warm Air Intake.

Picture of Using a Warm Air Intake.

I had removed my stock air intake assembly and put a re-useable filter on the throttle body. Warmer air causing the engine controller to use a slightly lean mixture means less fuel for normal cruising.

I dont think this is a good idea for aggressive driving since there is a power loss at the higher rpms but for me with my smooth, "drive and let drive" philosophy, it works great!

Step 7: Warm Up the Car BEFORE Driving It.

Picture of Warm Up the Car BEFORE Driving It.

When a car is started with an engine block at ambient temperature, it operates in an open loop mode with respect to the Heated Oxygen Sensors (HO2S). Once the temperature guage reaches that middle region then the engine controller will accept readings from the H2OS. When this happens then the engine goes into closed loop mode and less fuel is used for the power required from it.

Warming up for up to 5 minutes prior to stepping on the gas pedal also means the engine is well lubricated internally and of course will experience less wear versus driving off on a now started engine. This is what I chose to do with my car. If you don't wish you warm up then the power of choice is yours!

I had a remote starter installed in 2004 in my 1999 civic and I use it every time. That investment pays off!

Whether you live in a subsidized fuel market like me or have no subsidized fuel, idling even for a little bit prior to demanding load is a good thing for an engine. From large megawatt to smaller output engines, some degree of warming up is necessary.

Step 8: Reducing the Car's Weight.

Picture of Reducing the Car's Weight.

I dont mean tossing the spare tire and car jack. Please dont do something like that. I did some simple things suchs as:

1. Replace the stock lead acid with a lithium iron phosphate battery. From 40lbs the car now has to carry 3lbs of battery. Been working great since September 2013 and cranks the engine faster than any lead acid! The mounting hardware for the lead acid battery I removed as well. Here's is my instructable on that project!

2. Clean up the engine bay. I removed my stock air intake and certain coolant tubes for the cabin heater I never use in a tropical country.

3. Use aftermarket components for upgrades. I replaced my rear lower control arms with aluminum aftermarket ones for minor weight improvement.

4. Keep only necessary tools in the trunk. Dont overload with tools you dont need during a road side fix.

5. Use alloy rims.

These may not seem much in the way of a 1 tonne vehicle but every bit helps. I myself weight in at 166lbs so I'm no heavy roller.

Step 9: Turning Off That Air Conditioning When Needed.

Picture of Turning Off That Air Conditioning When Needed.

When overtaking or moving from standstill, a good tip is to manually turn off the air conditioning. Just press that AC button! When you are back up to cruise speed then switch it back on. Of course on really hot days, fuel economy be damned but this is a really helpful tip.

If you wish you can drive with the windows crack a bit. Having them fully down while on the highway introduces ALOT of air drag. I have been using my air conditioning everytime and I still get great range from my gas tank. Just a thought eh?

Step 10: Use Iridium Spark Plugs.

Picture of Use Iridium Spark Plugs.

At first I didnt want to acknowledge it but the appeal of long life spark plugs got to me. Iridium spark plugs even though more expensive, do last longer and according to the manufacture they produce a better spark and help fuel economy. Going on 6 years and my spark plugs still work great. I cant say for sure IF they improved fuel economy but I love the fact I dont have to change them as often.

Step 11: Keeping Idle Speed Low As Per OEM Requirements.

Picture of Keeping Idle Speed Low As Per OEM Requirements.

Most engines over time will drift from the OEM recommended idle rpm. Try to keep that idle rpm with the OEM recommendation which is actually the lowest you should go without risking stalling the engine. Most folks tend to carry that idle way up higher to do what? Who knows? When an engine is idling really fast, it is gonna burn up more fuel! Keep it low and keep it real.

Step 12: Install a Performance Exhaust Header.

Picture of Install a Performance Exhaust Header.

This is only viable in countries that do not have emissions testing. Performance exhaust headers allow easier exit of gases and the benefit of reduced weight. I'm not talking about a loud muffler here to wake up the entire neighbourhood. Leave the stock quiet muffler. Its just the exhaust header replacement to a less restrictive type that allows for a small improvement in fuel economy.

Here is the instructable for my manifold replacement.

Step 13:


carseatmedic (author)2015-12-31

All good ideas. I believe that any gains you're making are probably negated by idling your car for five minutes every time you drive it. Yes, your mileage will suffer when the engine is cold. But your mileage while the car idles is ZERO! This is particularly true if you live in tropical area; your car will warm very quickly, lessening the cold run time. I live in a four-seasons area and the only time I start my car before driving it is if I have to scrape the windows. Otherwise, I start the car and go.

dmwatkins (author)2015-06-10

I built an instantaneous fuel economy gauge (based on the MPGuino design) several years ago, and being able to see my fuel economy rate while driving has really changed my driving habits.

If you could clarify something you referenced for me: You state to coast downhill while in gear... If I coast down hill while in neutral or while holding in the clutch, my fuel economy reading skyrockets by about a factor of 6, while the engine drops to idle RPM. But if I coast down hill in gear, after a few seconds my economy reading will state "0."

Now, this is probably just a "divide by zero" issue and with the microcontroller. But as the reading is pulled from the wheel speed sensor and one of the fuel injectors, it seems to indicate that the fuel injectors are essentially turned off (and also fuel pump as well?) while coasting downhill in gear.... Is this true?

y1111 (author)dmwatkins2015-10-04

you can also qhen coast a downhill , put ion neutral and SHUT OFF THE ENGINE .

that will give you 0-zero fuel consumption and no resistance from the engine braking.

just hold the direction firmly as the hidraulic assistance will be turned off too

Hashem_Mehyar (author)y11112015-10-18

Modern cars shuts off fuel if the car is cruising, this method is bad because: 1-lost of steering assist 2-brake assist 3- no abs 4-turning on the engine uses alot of fuel (except start-stop systems) and the risk of steering lock !

very well said! I don't know why y1111 made such dangerous suggestions.

SpikeFiend (author)dmwatkins2015-06-11

You're not seeing an error, when coasting down a hill (or to a stop) in gear your cars ECU can shut off the fuel injectors. The cars momentum/gravity is maintaining the engine RPM with a fuel injector setting of "0".

Coasting in neutral (with fuel injection) will use more gas since now you need some fuel to maintain the engine idle on its own.

dmwatkins (author)SpikeFiend2015-06-11

All right! Thanks for confirming that for me. And by error I meant mathematically, as dividing by zero should yield infinity, not zero ;)

wolfkeeper (author)dmwatkins2015-06-15

Yes, that's right, and the extension of that is that ANY time you're slowing down, you should try to avoid using the brakes and just take you foot off the accelerator ahead of time so that you reach the right speed at the right time. That's way you won't be using fuel while you are slowing- and you'll be slowing for longer; and you want to be in the highest gear you can.

The exact way it works on virtually all modern cars is that whenever the revs are above a certain value and you have your foot of the accelerator, the fuel cuts out completely until the revs come down.

dmwatkins (author)SpikeFiend2015-06-11

...meaning a problem with Arduino's math library lol. If I'm dividing by zero, I wanna see holes open up in the sky, or at least the infinity symbol on the LCD!

Pkranger88 (author)dmwatkins2015-06-15

I agree. I have a Camry Hybrid and seeing that little bar shift back and forth calms me down.

stewkingjr (author)dmwatkins2015-06-11

US cars of somewhat recent vintage will shut off fuel when coasting in gear. Coasting in neutral is illegal in most states. That being said, if your càr slows down too much coasting in gear, the little amount of idling fuel burned coasting in neutral will easily be offset by overall gas mileage.

Joenavy85 (author)stewkingjr2015-06-12

yep, helps out big, but some of the little computers that plug in see this and think the engine is off and will stop recording mileage, so you won't see how much it actually helps. I downshift going downgrade when towing my trailer, helps maintain speed without using the breaks, and shuts off the fuel injectors. Long hills help the mileage number up a few points every time.

y1111 (author)2015-10-18

"coasting" when in gear will not be coasting anymore, will be engine braking. then you will loose velocity doing this because it brakes the movement, and then you will need to accelerate again to retrieve that speed and that will cost more fuel in the final results(even with the cutoff fuel system).

this is only made in when you need to decrease the velocity anyway or if coasting downhill(well but doing engine braking you will waste the potencial energy that could give you more speed when going down)

tmack0 (author)2015-06-16

If you drive an electric car that displays power readings, you will realize the savings from changing lights is minimal. Even electric bicycles have motors that rate in the 1KW+ range, my car routinely exceeds 85KW on heavy acceleration. Saving ~100W is barely a drop in the bucket.

Regardless, I changed my incandescent main bulbs to HID as they are much brighter at slightly less power, and changed all signaling lamps with LEDs as well for similar reasons. Between that and the life expectancy of HID and LED vs incandescent, its worth the upgrade. Be ware of LED front beams, there are many vendors selling bulbs that will fit, but put out pathetically minimal light, not suitable to actually drive with at night. Another warning in that using LED lamps can cause weird side effects with some ECUs. My Toyota tacoma will see an LED dome light as a short-circuit since there is minimal resistance, and turns it off (dim flickering, actually). A low-ohm high-power load resistor has to be added to make it actually work, same as the high-beam indicator with my HID lamps and LED turn signals, which brings the power draw back up.

y1111 (author)tmack02015-10-04

just the low light is 110w the pair , each rear brake and turn light 20w , each t10 little bulb from rear and etc 5w. so i estimated that can be up to 350w in lamps in a car thats about 0,5cv . 85kw as you said is when the car is accelerating ,when the car is on low load lets say 30-40km/h and 1500-2000rpm for gasolines ones it uses only about 30 or 40 cv (even if the maximum power is 170cv ,250cv etc) so 0,5cv compared to 30-40 is about 2-3 % less charge and its already a significant amount . i bought all the leds for my car on ebay for about 20-25 usd in total.

so i think this is a little but very simple ,cheap and great mod

Mjtrinihobby (author)tmack02015-08-24

My car is an old classic now. She doesn't fuss for any LED lighting. Newer cars might fuss but there are LED replacements that ensure compatibility with onboard power monitoring devices for those cars.

EsaE (author)tmack02015-06-19

In some countries, it's mandatory to have your lights (actual headlights, if you don't have modern daytime running lights) on when the car is moving. The savings will be more severe here.

kmartin45 (author)2015-06-11

Generally a manual transmission improves your mileage by about 10%. Outside the city, only sissies drive automatics (sorry). You just have to control the temptation is to take advantage of the extra torque. In my case, my manual '93 Honda Civic del Slow has no discernible torque (ok, large gaps). I have to wind up engine a bit to shift in traffic but still get 32 mpg city/38+ highway. And my old manual Toyota 2WD pickup used to get at least 33 mpg on the highway, for a cruising range of appx. 700 miles.

Some excellent ideas here... just a few thoughts. Yes, you save fuel coasting, but if you lose too much momentum, you're going to burn even more fuel climbing the next hill. Look ahead. That's my main tip for high-mileage driving. Don't accelerate when you know you're going to have to slow down. I don't find that "drafting" (using the slipstream of another vehicle) helps all that much. Even if you're not tailgating, you're at the mercy of drivers who slow down and speed up, which decreases your mileage. I have better luck backing off and keeping my speed steady.

Maybe someone can explain this weirdness, though. My 2013 Subaru (manual) gets a dismal 24-26 mpg if I drive it "normally." If I shifting very smoothly (without letting up on the accelerator all the way) and do a lot of engine braking, it goes up to 28-30 mpg on the same route, same speed. This seems counter-intuitive. I do save money on brakes as well as fuel, though: my mechanic has been asking for years whether I ever use my brakes... I just replaced them for the first time on my Honda at 149,000 miles. The pads were crumbling from old age.

j626no (author)kmartin452015-06-11

I could be wrong about this, but based on the instantaneous economy readout on my 2013 Fiat 500 Abarth, it appears that when engine braking, the economy shoots to infinity until I put a positive load on the engine. I would interpret this as the ECM recognizing the lack of load and cuts the fuel injection. This will especially be true if your car has throttle-by-wire as the computer can dictate the amount of fuel to disperse even when your foot is partially on the accelerator.

As for anybody wondering why a manual gets better fuel economy than an automatic, it is simply due to how each transmission engages the engine. With a manual car, you have a clutch that positively locks against the engine flywheel from friction. When you push the clutch in, it fully disengages -- during a shift, as you let the clutch out, it slips against the flywheel temporarily until is fully engaged. At this point it is a direct 1:1 ratio and no loss of rotational energy exists. With an automatic transmission, a torque converter is the link between the engine and transmission. The torque converter relies on hydraulic pressure to engage the input shaft of the transmission. Since there is no mechanical connection (ignoring lockup converters for simplicity), there will always be a certain level of slippage within the torque converter essentially wasting kinetic energy and converting it to thermal energy (one of the reasons automatic transmissions have oil coolers and manuals do not). I know I simplified this explanation, but if you're interested, I recommend looking into it as the complexities of automatic transmissions are very cool.

Lastly, I drive 50 miles a day for work and I have added some performance upgrades to my Abarth (Ram/Cold-Air-Intake to bypass the stock air box as well as an aftermarket ECM), and I average 28 mpg. This is with a 1.4L 4-cylinder that I can't help but drive with a lead foot (18 psi of boost is so much fun). With my upgrades, my car is putting out 180-200 hp (stock is 165). It only has a 10 gallon tank yet I only fill up once a week despite driving 250 miles just to and from work.

Also, tire pressure! Maintain OEM and the life of your tires, safety, fuel economy, and wallet will all benefit.

dmwatkins (author)j626no2015-06-15

Yep, the "infinity" question is the same one I had for mjtrinihobby the other day, and his reply as well as others confirms that some vehicles do shut off the fuel when engine braking

Mjtrinihobby (author)dmwatkins2015-09-29

Hey I never said that.

Mjtrinihobby (author)j626no2015-06-12

very nice reply. well said.

Mjtrinihobby (author)kmartin452015-06-12

thanks for the read and comment! First time I've seen a lady know this much about cars. I wish more women were like you. In my country, if the ladies happen to see under any hood they squirm and use interesting words.

juicer62 (author)2015-08-25

Couple of things here....I applaud what you are doing on your car! It's fun to see what one can do to increase fuel efficiency! But, also several bits of bad info crept in here. LED lights: can use less electrical energy, but are expensive still, and are subject to corrosion.....most never reach theoretical life before corrosion eats up the wiring or contacts; cost to replace overshadows any savings. Drafting behind other vehicles: yes, it is effective! You needn't follow closely to reap benefits---the mythbusters comment made previously is INCORRECT. I see my fuel usage decrease (accurate digital gage) just following at a distance in my vehicle in the wake of some of the turbulence, 5 or 6 car lengths behind. (I drive 105 miles each day, mostly on interstates at 70 mph. Fuel usage is critical for me!) Proof that that works you ask? Ever watch ducks or geese fly in a "V" formation? Ever wonder why? Ever hear or read about the difference in "starting friction" vs." moving friction"? Ever see the bulbous bow of a ship, the part that is under water? What is common to all these is that there is less friction moving an object through a fluid (air or water) that is moving slightly than through a fluid that is motionless.

Mjtrinihobby (author)juicer622015-08-25

Hey thanks for the thumbs up!

KalvinD (author)2015-06-23

I agree with all of these techniques for the most part. The only thing that I would say isn't necessarily needed is the "turn ac off when needed".

Your TPS or Throttle position sensor reads what percentage throttle you are applying. Anytime the computer reads WOT or Wide Open Throttle it will automatically disengage the AC. Anything more than like 70-75% is considered WOT, obviously this depends on the manufacturer and sensors.

Just my $.02

Mjtrinihobby (author)KalvinD2015-08-24

Sadly my car is so old she doesn't have that WOT setpoint to disable the AC compressor during hard acceleration. I'm developing a car automation PC to provide that feature and several others.

Thanks for the thumbs up.

dirizary (author)2015-06-11

I disagree on the lights. I have worked in automotive R&D and reducing electrical wastage is an area that is only just now being really pursued my manufacturers, earlier vehicles often have significant reducible electrical loads.

reducing copper costs by using too small a wire for the load is all too common. Incandescent vehicle lighting is a significant drain and switching to LEDs can easily be a third of a horsepower gain. When I worked in this field it cost us around $50,000 per horsepower to design more power into a system, gaining a 1/4 or 1/3 horsepower by switching bulbs is a no brainer... which os one of the reasons the manufacturers are doing this.

Joenavy85 (author)dirizary2015-06-12

1 gallon of gas = ~33.7 kWh. Internal combustion engine = ~25-30%
thermal efficiency. Therefore 1 gallon of gas makes about 8425 watt hours of
energy. If you reduce your electrical load by 100 watts (being generous towards
your side here) you get a roughly 1.15% savings per gallon of gas (assuming it
takes you 1 hour to burn it.). Now let’s say you pay $2 a gallon for gas, and
have a 13 gallon tank, you just saved 30 cents on a full fill up. Now let’s
look at cost for the LED conversion, I spent around $45 (I bought the cheap
ones) to convert all the exterior lights on my Jeep (except headlights and fog
lights), and it took me about 4 hours to install (we’ll take and $8 an hour
wage into account here) so the conversion cost me about $77 all together. $77 =
7700 cents. 7700 cents divided by 1.15 cents per gallon gives me 6695 gallons
before I break even. Now, we’ll say I only get the EPA average of 20 MPG in my
Jeep, that means I’ll have to drive 133,913 miles to break even, and that’s
with the lights on, but since the electrical load is constant we have to keep
the 1 gallon of usage per hour in there for it to stay fair. See how it’s
really not worth it? And adding even a 5 watt solar panel only bumps it to
1.24%, 6209 gallons, 124,193 miles, all with the lights on, all at a burn rate
of 1 gallon per hour.

mikeb071 (author)Joenavy852015-07-12

Here in the UK, we pay about $8 per gallon of gas.

dirizary (author)Joenavy852015-06-12

This sounds important. You should send this calculation of yours to GM, Ford, Mercedes, Audi, Volvo, etc so they can immediately stop their programs to phase out incandescent lighting in their products. It's sad that they will lose the hundreds of thousands they spent researching this.

When I saw lighting/wiring load testing done we saw a full third of a horsepower loss. Much of it in the form of heat. Of course we had a tightly controlled test environment, precision sensors, and an electrical engineer to analyse every component both in vehicle and on the bench.

Now I am not an electrical engineer (I primarily worked in braking systems) but as I understood it, the problem is one of cumulative effect. Incandescent lights use more power, their support (sockets, wiring) is designed as light and thin as possible to save weight and copper, which can produces heat losses, corrosion losses. The alternator is not a perfect machine and therefore takes more than than a horsepower to make 745.699 watts of electrical power.

In addition, incandescent bulbs make the alternator cycle on more frequently, which forces the engine to adapt power output accordingly. I saw where this was tested very methodically and the results were that a braking and turning signalling operation (which can easily mean 6 bulbs and a flasher unit demanding well over 100 watts) routinely made the alternator cycle on briefly, causing an idle increase when it ideally would be throttling down.

The bottom line is this. The automotive world has done the math, and automotive led lighting is rapidly becoming the standard. Home conversion is all about finding a good deal on quality bulbs.

kschmidt2 (author)dirizary2015-06-13

The last part about increasing Idle when braking and indicating makes me think that decelerating with the engine in a manual would help lessen that effect, in this scenario you're wheels are driving the engine and intern the alternator, meaning, technically speaking, when you're decelerating with the engine, you're also decelerating with the alternator which is well and truly making up for the loss of power caused by the alternator needing to cycle. Of course, this won't work for an automatic. Modern automatics don't utilise a rear pump (most modern auto's don't have a pump full stop) so they can't take advantage of engine braking.

Which is stupid if you ask me.

Joenavy85 (author)Joenavy852015-06-12

sorry, the final calculations were assuming gas at $1 per gallon, divide by price of gas as needed, i.e. $4/gallon divide by 4 = 33478 miles to break even.

Mjtrinihobby (author)dirizary2015-06-11

I knew I wasn't the only one with common sense! You tell that Joe guy! Common sense and knowledge is not so widespread apparently. Thank goodness for the instructables site for helping to educate. I think this guy dbess can learn a thing or two from you as well.

dirizary (author)Mjtrinihobby2015-06-12

I used to hypermile a couple of Geo Metro's, nothing advanced, but I got 51 MPG town, 67 Highway. Some of the hints in your instructable are fantastic! The LED switchover is so affordable nowadays, and your water injection is great, simple, safe (I have seen direct port water injection fail badly). Water injection was so popular for so many years, but many have kind of forgotten about it, except Volkswagen, who has been using it on their new 160 MPG diesel/electric test car.

Mjtrinihobby (author)dirizary2015-06-16

hey thanks man!

EsaE (author)2015-06-19

Super-capacitors+LiPo are almost a better combo already and don't weigh as much as LiFePo4 batteries.

Mjtrinihobby (author)EsaE2015-06-19

Lithium ion and lithium polymer batteries are very dangerous for high power applications unless supervised properly. Only ev will use this technology. For engine starting only Lifepo4 to date can safely fulfill that requirement to date. I will never use Lithium ion or polymer in my car.

EsaE (author)2015-06-19

Get Low rolling-resistance tires too

K-Note72 (author)2015-06-16

I was about to mention the cat issue. Catalytic converters are standard on cars here in the US, mainly because of congested states like California but I don't live in Cali. My first vehicle was a V8 pickup, I swapped up to a sport air filter and scrapped the cat and muffler for a straight pipe & stretched muffler. That and my easy driving habits took my mpg's from 13 to 21

Pkranger88 (author)2015-06-15

Shifting into neutral when not under power won't hurt your tranny. It only becomes an issue if you are applying the accelerator pedal when shifting in or out of drive.

If you are experiencing grinding noise when shifting out of drive or into drive, your tranny is screwed for other reasons.

Mjtrinihobby (author)Pkranger882015-06-16

I was referring to when my car is in motion. The lock up clutch on autos dont like that sort of thing.

MartyJ1 (author)2015-06-11

Are you sure about allowing the car to idle for 10 minutes before moving? That seems like a terrible waste of gas. I would think that moving, even inefficiently, is better than just sitting still.

tristemono (author)MartyJ12015-06-15

Here at 45 North, on the banks of the Mississippi, about 4 months a year, a car is intolerable before 10 minutes of idle. We are total nutbars about remote starters here.

Mjtrinihobby (author)tristemono2015-06-15

Most folks dont understand the importance of warming up an engine. Perhaps they should insist a pilot take off immediately after a plane's turbines are started? Idling prior to leaving home, idling in traffic, demanding WOT on highways all involve fuel usage and EVERY gasoline/diesel fueled engine produces pollution. We dont live in all electric drive age with reduced pollution but everyone likes to be a critic.

I like your point there tristemono.

d_j_h (author)2015-06-11

Actually dreiduke is making perfect sense, even if his grammar is less than perfect. Let me explain for you as best I can.

- I believe you will find combustion is more efficient at lowerair temperature. The air is denser at low temperature so you get more oxygen in your chamber, more complete combustion, and greater expansion of gas (bang power).

There's a reason they put cold air kits on - to get more power. How to you get more power from the same engine? Better efficiency!

Think about it: Your power in the cylinder comes from expanding cold dense air into hot sparse air. Putting hotter air in is, frankly, just dumb.

In real world tests, my old 320i can reach 108km/h up a certain hill in the cold and 97km/h in the heat.

- I bought genuine alloys to replace my genuine pressed steel wheels. They are around 1.5kg heavier. Each. The steel is denser but it's a lot thinner.

- Run the ventilation fan instead of the A/C or opening the windows. You are right about the drag of both.

- If you know you will have to stop in a few hundred metres, lift your foot and roll up to it instead of braking hard at the end.

Mjtrinihobby (author)d_j_h2015-06-12

Hey dude it's cool. You were just being passionate about your comments same way I'm passionate with my projects. All points taken though in good stride. Stay tuned for some really interesting instructables that I aim to publish very soon.

dreiduke (author)Mjtrinihobby2015-06-12

the only situation where a "hot air intake" makes sense, is during the warmup phase, to bring the engine asap to operating temp, where the oil is less viscous, and the cylinder walls are hot so no fuel is condensing at it.
(by the way, this is the reason for high fuel consumption with cold engine, high viscous oil and condensing fuel at cylinderwalls, (this is by the way also the reason for "choke" or auto choke on carburetor engines, to increase the fuel air ratio, to compensate the condensation )
In other words, try to get the Engine warm, as fast as poss. (may be with hot air inlet, (old VW Golf make this automatic with bimetal, during warmup and cold outside temp, the bimetal is powering a flap which deflects tech intake air around the exhaust manifold)
And when ops temp is reached, try to hold the Air inlet temp as cold as poss. This will end up into maximum efficiency, and when u not change your driving style, (smooth, providently) u WILL safe fuel.

Please stop taunting. Try it and/or connect an ODB-Bluetooth adaptor (about10$, and the smartphone obd app "torque" is free) and u will see it.
and for proofing it, u can build a flapsystem with some pipes to switch hot (under hood) air to much more cooler outside air, while driving.
And u will see.

d_j_h (author)dreiduke2015-06-13

Light aircraft also use this is system. It is called "carburettor heat", using a similar method of taking in air from over the exhaust manifold. It's turned on before starting and always turned off, once warm, before take-off.

Heat has multiple important functions. It helps the engine warm up faster as you describe in the VW. The prime function is making sure there is no ice in the carby caused by humid air freezing.

A major side effect is a significant loss of engine power.

Mjtrinihobby (author)dreiduke2015-06-12

start your very own instructable, its a very good feeling you will get especially when you recieve the world of comments. start today!

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Bio: As of April 2017 I have decided to no longer post on instructables. The fact that several of my published works have been removed without ... More »
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