Instructables

Step 9: Acceleration

Picture of Acceleration
The best way to accelerate is by keeping your engine at peak torque. This means, accelerating too slow (as you may have been told to do) and accelerating too fast (bringing your rpms up high) are inefficient and will reduce your fuel economy numbers.

Ideally, peak torque at 50-75% throttle.
 
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JustinC41 month ago

Nope. This is false. I have an OBD Bluetooth connection to my tablet. This method sucks up fuel like a sponge. A nice slow acceleration is what is best, besides truckers (who have Standard Transmissions) do the same and they're all about conserving fuel. My car is an automatic.

danwat12343 months ago

Keep in mind, if you have a torque converter automatic, trying to make the transmission go to lock-up or soft lockup as early as possibly is good for fuel economy. The more a torque converter slips, the more waste heat end ups up in the transmission. Also if you press too much on the gas, the engine computer may have the engine run rich, as in lower than 14.7:1 air to fuel ratio.

A scan gauge or torque smart phone app thing can help with this

jimmytvf4 years ago
that's what i'm talking about, playing with throttle and RPM. Low rpm = low fuel --> FALSE Low rpm make the time lapse between injections increase, so we get less fuel in a second, that's true, but, if we have to step more the throttle to get the same rpm, the volume of fuel increase, and the car needs energy to move and spend more fuel. you have to play with what your engine needs and, at the same time, manage the efficiency of the fuel you send to the engine
best rpm shiftings on petrol: 2000 to 2500 RPM
best rpm shiftings on diesel: 1500 to 2000 RPM (lower rpm torque point)
trebuchet03 (author)  jimmytvf4 years ago
To your earlier comment - this is why instantaneous fuel economy data is important ;)

Yes, we care about long term average consumption - but you won't get good long term averages if you can't keep your instant consumption low (as you accurately said: "play with what your engine needs").
yes, i've just realize about that ;)
horta_126 years ago
I read many artikles on this topic that stated you should accelerate slowly; so I did. I was accelerating with my RPMs below 2k and usually lower. It only took me two commutes to notice my fuel gauge drop significantly faster than it should have been. It was actually dropping faster than when I was driving aggressively. Basically, I'm just verifying with my own experimentation that there is a happy medium between accelerating too fast and too slow. I would say a broad estimate for most cars these days would be about 2k to 2.5k RPMs. Thank you for the good information.
Outlander7 years ago
This is a very old step, since cars have been around. It's called the "power band" Basicly going below the power band is called "lugging" the engine and going over the power band is just wasting fuel. If your car develops near peak torque at say 2,500 RPM, always accelerate near that RPM. If one is lugging the engine(accelerating below the engines power band), then it is just wasting gas as the engine struggles to accelerate. The only time when going below the power band will save on gas is during highway cruising when all the throttle one needs is done by "pulsing" to keep the car at a certain speed. Basicly pulse the throttle+ low RPM + near constant velocity will save on gas.
crestind7 years ago
Can you explain why 50% would be best? I usually accelerate slow enough so the needle doesn't go up and shoot back down (don't know what that's called...)