How to Save Petrol, Save Money and Save the World!

Introduction: How to Save Petrol, Save Money and Save the World!

Petrol is getting really rediculously expensive these days and scientists say that if we don't do something to reduce carbon emissions within 5 years,permanent climatic change would have taken place.If i had my way i'd buy an electric car tomorrow but unfortunatly im still a student.

Here are some methods i use to get 50% more fuel efficiency out of my 2 litre diesel toyota.It sounds impossible to get 50 whole more percent but the internal combustion engine and the way we deliver the power to the wheels is extremely inefficient process, but it is easily achievable.

Before i started driving more efficiently i used to get about 10miles to the litre and now i get about 15 to 16miles per litre.It sounds like nothing extra but do the maths.

previous fuel consumtion at 10m/l = 200miles per 20 litres
new fuel consumption at 15m/l = 300miles per 20litres

so i get another 100miles "from nothing"!

Only about 20% of all the energy in petrol or diesel is converted to motion, the rest is wasted in heat, vibration, noise, which i think is just not good enough and thats why i think that the internal combustion engine is an old technology in need of retirement or at least semi retirement and used in hybrids.

There are 5 steps to increasing fuel effiency:

Drivers Attitude
Velocity or speed

Step 1: Resistance

Resistance on a motor vehicle is broken down into two different forms:Roling resistance and air resistance..

To reduce rolling resistance:

I always fill my tires to their maximum inflation pressure or maybe about 2 psi under,the higher the pressure the less surface area in contact with the road and therefore the less resistance therefore the less energy required to move the car along.The negative side to this is to fill the tyres with too much air,and the life of the tyre will be reduced because it will wear out in the middle of the tread so you need a good balance(usually about 2 psi under the max pressure printed on the tyre)This will probably increase overall efficiency by about 5-10 percent.

To reduce air resistance:

There isn't really much you can do to affect this one because as we all know the vehicle is a fixed shape and we cannot change it.But if say you have roof racks on the car,this can effect the resistance a surprising amount so take them off when not in use.Also a shark fin low profile type aerial is more efficient than a stalk aerial.Taking these off will increase overall efficiency by probably 5%.

Step 2: Momentum

This one takes a while to get used to,you basically have to change the whole way you drive.It basically involves using your breaks as little as possible and keeping the car moving.It also makes you a much more careful driver because you have to plan ahead.Slowing down with your gears helps amazingly, because apparently modern IC engines use NO fuel when doing this.This saves quite a bit of petrol.

Step 3: Acceleration

Most people just race off from a traffic light or from a stop without giving it much thought at all.But the slower you accelerate the less fuel you burn, whats the rush anyway, you'll probably only get to your destination a few minutes earlier and more dangerously anyway.a=(v-u)/t so if u spend a longer time climbing to a speed versus a shorter time your acceleration will be less and fuel consumption is greatly reduced.Once i discovered this i started saving petrol like you cannot believe.

Step 4: Weight

This one is pretty obvious.Take all the excess shit out your car that you don't need.less weight,less energy for the engine to have to put into the car to make it move, simple as tomato paste on bread.

Step 5: Driving Attitude

This is definatly THE most influential factor when saving fuel.The mood you're in greatly influences how you drive.Drive slower and allow more time for your journey (get up 5 minutes earlier)accelerate slower break less and use your gears to slow down you'll be amazed how much fuel you can save.

Step 6: Velocity

Velocity or speed is the final factor.

Did you know that if you double your speed, you quadruple your drag due to air resistance, yes, its go slower.I travel at a maximum of 40 mph(or the lowest speed you can go in the highest gear you have)40mph might be a bit rediculous for some but even reducing your speed 10 or 20 mph can drastically save fuel.anything over 60mph basically just wastes fuel.



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    41 Discussions

    best thing you can do to your vehicle to save fuel: adjust the nut behind the wheel!

    my dad uses a fuel magnet it increased his mpg my 17 mpg before it was 30 mpg now its around 40 to 50

    If you save 50% with all those tips you must have been driving like a lunatic before you used them. Normally you will save around 24%.

    I am using automatic transmission car...though my car fuel consumption is significantly low,I want to reduced it further...are your tips aplicable for my car as well or it just for manual transmission cars only....

    I have always took it easy on the car, like letting my foot off the gas and coasting to stop signs. Plus i own a motorcycle which really saves on alot on gas in the summer months. But doing 40 mph is quite hard living around a city trying to get home on the freeway, heck you'll get run over. Driving a hybrid car would be a better option.

    Sheesh, peeps, get a friggin hybrid! It may increase smug levels, and you can't help loving the smell of your own farts, but it's worth it (if you watch south park, you'll know what i mean) but don't be gay and get a Priass, get a camry hybrid (unless you're a mpg fanatic, then buy a Prius. Yes.)

    4 replies

    Hybrids? What? I drive a 1991 Honda CR-X I got for $2000, and i get 45 mpg roughly following the steps above, better than many hybrids get. Cheap and fun to drive, too. There are lots of older cars that get great gas mileage, I actually don't know why new cars get such terrible mileage, but if you just research and look around you can find a good, reliable, affordable car for about one tenth what a new hybrid costs.


    not all of us have tens of thousands of dollars to put into a friggin hybrid! On top of that, hybrids only use the electric motor up to about 20 mph. This will only affect the initial acceleration. This does help alot, but how long do you have to drive a car like that to get enough benefit to make up for the thousands of dollar spent on a hybrid compared to the gasoline model??

    ah, touche, uberchoob. not all of us have a boatload of $$$ to spend, and i think the ev mode kicks into gasoline at 42 mph. about your bit on how long it'd take to offset the cash spent; it's kinda like a solar powered house..if you want to be cool 'n casual when you drive (driving like a normal gas car) it might take longer, but if you want to hypermile (constantly using ev mode and pissing ppl off in the process, and maybe, just maybe, getting shot for being a stick in the mud), then it will definitely be less of a wait. i hope to try hydrogen fuel cell or biodiesel cars when they come out, as i already know how to make biodiesel. and totally_screwed is right, nitrogen improves fuel efficiency because it lasts longer, and it doesn't change with the weather (shrinking when the weather is cold, expanding in heat, so it's less wear and tear on the tires AND your wallet) sorry if this was too long of a response, but i was answering your question properly and trying not to type like a drunken 4th grade rockstar. Arrivederci!

    shut up you.....uhh...................camster! yeah! take that man....and stuff....=P jk dudeo

    Underinflation does not increase traction. Tires are designed for maximum traction at an optimum tire pressure. If the tires performed better at a lower pressure that would be the pressure listed on the side of the tire.

    Can't help but wonder why you aren't using used vegetable oil if you have a diesel... You can even use 50% cleaned oil straight into the mix without a conversion kit if it's warm enough outside. Do a Google seach for "Greasecar" and check out their conversion kits. The car starts on diesel in order to warm up the vegetable oil (if it's too cold outside) then you switch to veg. oil. No pollution, smells good, and same or better performance as conventional diesel fuel has been reported. Plus the fuel is free-- most restaurants PAY to have their oil hauled off and would be highly inclined to let you have it free. It is very easy to purify the used oil at home, especially with a kit.

    "But the slower you accelerate the less fuel you burn,... "

    Careful... not 100% accurate - but its easier for the masses to understand. Vehicles that have adaptive control will keep the same a/f ratio while in closed loop (where fuel trim is directly adjusted based on sensor feedback). Certain events will cause the computer to go into open loop (events such has a preset throttle %, detected sensor failure, warm up enrichment programs).

    On my last car, this happened at around 80% throttle. I discovered this with a signal monitor attached to my O2 sensor. If you have the money, or know someone with a fancy OBD2 interface (if your car is OBD2 compliant) - you can find out actual numbers and get stored trends out of the box :)

    I'm not sure what my current car does - it uses a wideband O2 sensor - so the 0-1v voltage comparator won't work on it :P

    Something to add to resistance... Internal resistance plays a HUGE role too. Keep up with oil changes. 3K miles is a little early in my opinion (disturbs oil films too often). But keep oil at the max correct level and use a quality oil. What's a quality oil? Can't say - you'll have to do oil analysis on used oil to see how your motor handles it (this testing costs $20). Also DO NOT overfill. You'd be amazed at the viscous losses you'll have if your crank (or counterweights) is in contact with your oil.

    4 replies

    One way to learn to drive more efficiently is to get a car that is not overpowered...The car companies want you to think that you need a 350 hp, turbo-ultra-super-dupercharged V-8 that requires 95 octane fuel to haul you to the grocery store at 35 mph. I drive an old (1980) electric truck around town, with a 20 hp GE motor. No power brakes mean that you learn to slow down earlier, and lower power means you learn that accelerating to the red light at the top of the hill doesn't always work out...On the other hand, that time I popped the clutch into first and kicked that Camaro's butt was pretty cool.

    "Overpowered" and "lower thermal efficiency" are not synonymous terms. However, fuel economy would be related to a small vehicle with an large powertrain. This is why engine management is very important to keep that stoi. a/f ratio -- keeping in mind that it takes the same amount of energy to accelerate a given mass.

    Oh... I also forgot to mention another thing...

    LOWER RPM does not mean HIGHER fuel economy. However, LOWER LOAD is related ;)

    I found that in a high gear under heavy load (say final gear at 25mph) - my fuel consumption goes up significantly (and into open loop). Your car's computer takes into consideration engine load (which is measured based on a variety of inputs including throttle %, engine speed, etc.).

    Otherwise, you make very good points... weight is a big one, saves a lot while accelerating. Weight is not as big a factor once you're at momentum (that would be due to wind resistance) - but if there's a significant amount of excess weight, rolling resistance may become a significant factor ;)

    Also, Mitsubishi published a technical paper on vortex generators several years ago... Apparently, they actually do reduce cD by .006 (for those that don't know, that is in the realm if significant) -- but a damn ugly in my opinion :P

    I meant highest gear possible at lowest speed,within reason.My car struggles in 5th gear at 35mph and that will obviously eat petrol.At about 38mph it becomes pretty easy for it in 5th gear so i just go a minimum of 40 in 5th,i basically try not to let the car go lower that 2500rpm otherwise it struggles and not much higher than 3000rpm.Also i have been told that all toyota diesel engines apparently turn into air compressors when coasting in gear, i was skeptical of this,but when i used to coast in neutral i did burn quite a bit more diesel and also obviously its not as safe to coast down a massive hill with no gears if your breaks fail.Also tapping the breaks for short periods of time increases wear rather than pushing them hard for a long period...