Driving standard for mileage question

I drive a 2001 Sunfire with 2.4 L, wondering what rpm would be best to shift at for best mileage. I see in other posts around 3,000 rpm is good, and that makes sense given how the car feels and sounds at that level.
How about the lower range? Is it more economical to keep rpms as low as possible to go to the speed you want without lugging down? I find myself in fourth gear at 60 kph/37.5 mph and around 1,500 to 2000 rpm. Acceleration sucks, yes, but I'm not real concerned about that. But does that just suck more gas?

around 2.4k rpms is around the best for best gas mileage. my '97 sunfire is an AT and that is when it shifts. it is more economical to stay at a lower rpm range so it is less air and fuel the engine needs to suck up. and no it doesn't suck more gas up basically the higher rpm the more rotations per minute it has to do and the more air and fuel it needs to take in.

The amount of fuel you use is a factor of three things in an EFI car.

1) The position of your right foot. The less throttle you have open, the less fuel its using.

2) The RPMs of the engine. Combined with #1, the engine reads how much air is coming in. Even if your foot stays in the same place, higher RPMs inject about the same amount of fuel, but much more frequently.

3) The amount of change in your right foot. Going from 1/4 throttle to 1/2 throttle uses more fuel than just the increase in airflow requires. Adding more foot requires a temporary enrichment. So, what that means is; if you compared how much fuel it takes to accelerate at 1/3 throttle, then compared it to the amount of fuel you used by accelerating using varying positions between 1/4 and 1/2, the latter would use more fuel since every time you push the pedal down, it has to squirt some extra fuel to compensate for the rush of air coming in.

Acclerate using the least throttle necessary with as little change as necessary. That helps you two ways. The steady foot prevents the acceleration enrichment, and the small throttle opening uses little fuel. The rest you'll have to judge by yourself....

Start paying attention to where your foot is. If you shift to early, you'll need more right foot in the next gear to maintain your rate of acceleration and that sucks fuel since you're bogging it. If you need less right foot to get the same acceleration, you've used more fuel in the previous gear by spinning the engine faster.

If you live in a flat area, chances are you can drive it like granny and shift as low as 2k, provided you're not looking for quick acceleration. If you add some hills to the equation, then you'll have to start paying attention to your right foot after the shift. It doesn't take much of a hill to make the engine bog down and require lots of right foot to compensate.

As you're factoring all of this in with hills and right feet and RPMs, an important thing to remember is that high RPMs and a light foot use less fuel than low RPMs and a heavy foot. The demand for fuel increases faster with your foot than it does with RPMs. Although I said its ideal to shift where you don't create a bog, nor do you waste RPMs in the previous gear, its usually safer to err on the side of shifting a tad later to prevent bogging it down. The best mileage will come from the proper shift point, but shifting too late uses less fuel than shifting too early. The bog you create in second gear uses more fuel than if you had held it with a light throttle in first for a few more hundred RPMs.

well for what i see... lower RPMs = less gass used... i have a 1998 v-6 AT cirrus... i can keep it at about 2000 RPMs at 55 MPH i sorta make it shift at 40 and it drops to nothing... if im running on low gas... i can go... FOREVER

3) The amount of change in your right foot. Going from 1/4 throttle to 1/2 throttle uses more fuel than just the increase in airflow requires. Adding more foot requires a temporary enrichment. So, what that means is; if you compared how much fuel it takes to accelerate at 1/3 throttle, then compared it to the amount of fuel you used by accelerating using varying positions between 1/4 and 1/2, the latter would use more fuel since every time you push the pedal down, it has to squirt some extra fuel to compensate for the rush of air coming in.
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Excellent answer, but here's a question......I thought this fuel enrichment only applies to a carbureted car, from a device called the 'accelerator pump' and does not occur with an EFI car due to the more precise fuel metering inherent with EFI?

Excellent answer, but here's a question......I thought this fuel enrichment only applies to a carbureted car, from a device called the 'accelerator pump' and does not occur with an EFI car due to the more precise fuel metering inherent with EFI?

The EFI does it almost the same, albeit more efficiently. When the throttle plate opens (indicated to the ECM by either the TPS or manifold vaccum) the ECM enriches the fuel substantially to keep the engine from stumbling. The nice thing about the EFI car is that it examines all the required parameters (engine temps, ambient temps, rpm, air flow etc.), to enrich only the required amount, whereas the carb is a bit sloppy.
But in either type, keeping the thottle consistant is best.

Jim
SR Racing

An otto engine consumes less fuel per kWh the more throttle you use, NOT the other way around which have been mentioned here.

For the lowest fuel consumption you want to drive with the highest load/lowest engine speed possible. When accelerating, do it fast and then go to the highest gear possible. This means that when acceleraing to can floor it unless you care for exhaust emissions. If you also want to drive environmental friendly don't go over around 3000 rpm and half throttle (this is to prevent the engine from running "open loop").

One of the most important things to keep consumption down is to not stop unless you must, don't use the brakes unless you have no other choice and don't drive too fast.

One of the most important things to keep consumption down is to not stop unless you must, don't use the brakes unless you have no other choice and don't drive too fast.

Amen to that.
Not only does it help with mileage, it also extends the lifespan of your brakes! (Another "pro" for manual transmissions!)

One of the most important things to keep consumption down is to not stop unless you must, don't use the brakes unless you have no other choice and don't drive too fast.

Definitely! If you see a red light ahead, don't go flying up to it and slam on the brakes. Just slow down a little bit(probably just coasting) long before you get there- it will probably turn green before you get there, and you won't have to stop at all. Accelerating from a stop, that pull from 1st and 2nd uses a lot of fuel.

Also leave plenty of following distance. I see so many people that drive 10ft behind the car in front of them, and every time someone slows down a hair, they have to slam on their brakes. If you leave a little distance, all you have to do is lift off the gas pedal a bit, and you might start to catch up to them at first, but then they'll speed up again(wasting gas) while you're just cruising right along at nearly the same speed.

Or just buy a diesel. :evillol: