How to Improve Your Car Efficiency




About: As being a long term unemployed, because nobody wants to hire anybody with no professional experience here in Spain, I have to tinker how to make stuff without getting broke, for the things that break down, ...

In this instructable i'll give you some tips of how to improve your car efficiency in little things that you never notice.

This is my first instructable, you can bear me with my english, because I'm spanish and I can make some little mistakes

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Step 1: 1. Let the Car Warm for Itself While You're Driving

Don't let the car for a while idling for warming, you can drive wherever and by the time, your car will get warm by itself, and you'll save, time, gas and you won't emmit so much gases to the atmosphere.

Step 2: 2. Drive Responsively

Street roads, aren't for racing. Every traffic signal is designed to go for a determined speed to reduce pollution, noise, and increase safety. Driving with a little common sense, you'll gain in safety, in pollution and in police fines.

Maybe sound like grandpa drives, but this way, you'll save gas, and you won't emmit so much gases, and car's parts won't get worn so fast. Doing burnouts, heavy stops, and heavy starts, you're losing money without realizing.

If you want to race, go to a circuit, with a few friends, and race there, there's no speed limit, and i'm sure, you'll have a great time playing with your car with your friends. And a day of action with your car, doesn't matter if you emmit gases, worn parts or waste money, beacuse is only a day, a fun day, as a beach day or something, not an every day drive :P

Step 3: 3. Change Gear

In manual transmissions, people are in the order to change gear about 2500-3000 rpm on petrol, and 2000-2500 in diesel engines.

I have a '95 Ford escort with an 1.6 EFI engine, and i usually change gear in order of 2000-2500. the car has the enough power to keep dragging the weight of the car without spending more gas that's necessary for driving.

In diesel engines, the peak of par is at the order of 2000 rpm, so, i supposed, that the effect of changing a petrol engine in 2000-2500 rpm, in a diesel would be the order of 1500-2000 rpm, in the maximum par range, the zone that the car makes the maximum transfeering power to the wheels, so, in diesel, is even, more efficient

Sometimes, when I'm starting to run out of fuel, i change gear in orders of 1500 rpm. sounds kinda strange, but the car stills going forward and I procure spend the less gas as possible.

Maybe the car won't be enough warm, but is a great way to optimize the fuel use at the maximum level

Step 4: 4. Aerodynamics

Improving aerodynamics is a factor that determines, in a medium wave, the efficiency of the body of the car.

Improving this aerodynamics, you'll gain in less force that has the car to make to drag his own air friction, in a consequence, more gas spending, because the more force has the car to make to go forward.

Ok, leaving away this technical explanation (yes, I'm a car technician, what you want me to do :P) i'll show you some little tricks that make some reduction of the aerodynamic force that goes against your car.

that's a little guide that shows the amount of gain or losing aerodynamic force. Gain means, more gas spending, and losing force, less gas spending

lowering the car 30mm -5%
flat wheel covers -1 to -3%
wide rims + 2 to +4%
windows at the same level of the body -1%
filling gaps (doors, windows...) -2 to -5%
underbody shape (as flat as possible) -1 to -7%
retractable lights + 3 to +10%
side mirrors +2 to +5%
air flow through the engine bay and
radiator +4 to +14%
brake ventilation +2 to +5%
ventilation of the interior +1%
open windows +5% (notice that the air conditioning,
increase more the dragging force of the car
against him, so is preferible to go with
open windows instead of A/C)
open roof + 2
surf board in roof +40%

this board are approximations of the real values, because are lots of dependants that are involved in the modification of this values.

Step 5: 5. Some Mistakes About Car Efficiency Tips

You usually heard that some ways to spend less amount of fuel is, for example, turn the engines in stops, if are longer than 30 seconds. Well, is true that you save some gas stopping the engine, but that's not true as people believe.

In carb engines, the theory is false, because carbs need an amount of fuel to get the car started, i mean, a rich mixture into the engine, to get a correct startup.

In an EFI engine, the theory is correct, because injectors, don't need that amount of fuel as carb engines need, the CPU constantly calcules the correct amount of fuel

But in real life is completely wrong, because the engine needs lubrication and if you're constantly starting and stopping, the contrast of temperature, of cold-hot-cold-hot, it affects to the engine durability, because happens the same thing as the desert, days are extremely hot, and nights extremely cold, that's the reason of the sand, the rocks crack, and crack again, making that "mini rocks" that's the sand.

That's one of the consequences.

Another is, if you start and stop the car, the piston is hot, because the heat of explosions, the piston expands, and needs the lubrication of oil to make a wall that separes the hot piston with the cold block. Ok, so what happens if you cut the oil flow inside your engine?

You're always see on winter people that get sticked his tongue in a frozen metal part when they lick them. In the engine happens somehow something similar, the piston is the tongue and the block the frozen metal, so you can throw away your engine, because the piston is welded to the block, and you can't do nothing for save it, even the cranckshaft, because as the repentine stop, the most probably is that the crankshaft breaks and make a very cool mess.

Well, as I say in step one, that's my first instructable, thanks for watching! all the comments, and constructive crytics are accepted ;)

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    14 Discussions


    10 years ago on Step 1

    All car manufacturers design engines to operate while hot. Not letting an engine warm up to operating temperature during cold times causes accelerated wear and shortening of engine life. Diesel engines are especially prone to this, even modern ones. How much is debatable, but nonetheless true. An engine while idling produces a very tiny fraction of HCs compared to normal city driving. Pardon my poo-pooing of the poster's suggestion, but this is a myth.

    1 reply

    8 years ago on Step 4

    Hola, a partir de cierta velocidad la mayor parte de la energía que gasta un vehiculo, se usa para vencer la resistencia aerodinamica, por tanto mejorar la aerodinamica del vehiculo es el punto principal para reducir el consumo.
    Respecto al aire acondicionado de los coches, en los modelos que he probado, (modo A/C recirculando, vehiculos c5 y l200) con los medios convencionales no es posible medir diferencias de consumo entre llevarlo puesto y no.

    Buen instructable.

    Hi, at certain speed most of the energy used by a vehicle is used to beat aero drag. So improve the vehicles aerodynamics is the key.
    About AC, in the models I've tested (a/c recirculation, car c5 and L200) with conventional means it's not possible to tell any differences wheter it's on or not.

    Nice instructable.

    1 reply

    Reply 8 years ago on Step 4

    soy tecnico superior de automocion, y está demostrado ese resultado. Normalmente estas pruebas se hacen a velocidades de mas de 100 km/h, donde la eficiencia aerodinámica es la clave. Esta ley se aplica cuando el aire fluye alrededor del lado del coche. Con las ventanas abiertas, el aire choca con el pilar de la ventana, aumenta la resistencia aerodinámica, en cambio, con las ventanas subidas, el aire resbalará por asi decirlo, en vez de chocar.

    I'm a superior motor technician, and that results are tested. Usually that kind of test are made in speeds up to 100km/h (60mph) where the aerodynamic efficiency is the key. This law works when the air flows through the side of the car. With the open windows, the air his the central pillar, the aerodynamic resistance is higher, but, with the closed windows, the air will slide the glass instead.


    9 years ago on Step 5

    The "Spanish English" was a bit of a struggle in places, but the meaning was clear and a lot of good advice - Thanks.

    2 replies

    Reply 9 years ago on Step 5

    not sure what you mean, but thanks for told me that i made a kinda clearly instructable


    Reply 8 years ago on Step 5

    some of your wording is off but other than that i liked the hole instructable and i still did understand


    9 years ago on Introduction

    We started diesels and gasoline engines in beastly cold temps daily, and got 400K up to 800K miles on 'em with minimal warm-ups.
    Staying in the highest gear you can w/o 'lugging' the engine saves fuel.
    Better - when we go to the city, we park at an outlying mass-transit station and slide into downtown in our public electric trains! No through-the-roof parking lot fees or bright orange $25 valentines on the windshield.
    Really, you want to get around efficiently? Fight for light-rail transit.
    Boston is very well served. Of course, they've had it since 1874

    1 reply

    Reply 9 years ago on Introduction

    that's the most efficient thing you can do, of course, but here in Spain, trains are the worst thing you've got to move around the city always with delays, and for 0,78€ a trip, isn't so bad


    9 years ago on Introduction

    As a retired 18-wheeler jockey I still 'play the lights' , backing off the power and cruising up to the red light as it goes to green and going on w/o using the brakes at all.
     I am not electro-psychic, one does get so one 'plays traffic like a violin.
    Try it - you'll save gas. Of course you can't do it always and everywhere,  and patience is un-American.
    I figure I  get a free annual dinner out with my wife, not to mention going further on brake pads.


    10 years ago on Step 5

    Well said. Too many myths abound concerning increasing gas mileage, and you see the "stop the engine at traffic lights" often. It would be interesting to see a study done on how much undue wear is created from some of these myths such as driving a cold engine and short-shifting (not letting an engine operate at medium RPMs where the volumetric efficiency is far higher than at low RPMs).

    Your tongue on the pole analogy is completely wrong. Engines lock up because the piston expands faster than the block. This is why you should let your engine idle and warm up before driving. Its a huge deal in older sleeved engines, not as big a deal in aluminum engines.

    2 replies

    yes, you're completely true don't know what i've been thinking in that moment with the analogy, but i put the correct explation a little more forward thanks for the advice!


    Reply 10 years ago on Introduction

    well, i want to say that the explanation of because the piston expands faster than the block, is because the no-lubrication with the difference of temperature, that makes that contrast that don't allow the piston contract at the time that it need to return at his original status. oil that makes, one of his missions is to evacuate the heat, and separate this two parts, the piston and the block, so, the piston don't "overexpand"