As i was driving on my way to work, I saw the gas prices, and I started to think about optimal speeds at which my car would have the best fuel efficiency. So my question; is there anyway i can find out what would be the best speed / rpm I would have to drive at to achieve good fuel efficiency while cruising on the highway? I have a 2000 Honda Accord LX 4dr Automatic

The reason i'm asking this is because, in airplanes, the manufacturer provides the pilot with certain engine power settings, which in return promise you the pilot a certain amount of gallons per hour being used during cruise and other stages of flight.

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the speed limit was set with gas efficiency in mind. mind you that was a long time ago...... your best bet is trial and error.

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Originally posted by Halcyon+On+On OOKA-OOKA ME NACHOS ME PRESS KEYS ON COMPUTER GOOD

your car's user manual should have this in it.

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In general, smaller, lighter, more aerodynamic cars will get their best mileage at higher speeds. Bigger, heavier, less aerodynamic vehicles will get their best mileage at lower speeds.

Vague answer, I admit. But the question is complicated to begin with.

Read this : http://auto.howstuffworks.com/question477.htm

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Originally posted by twilightki : It feels like something you'd listen to at 4 in the morning, or listen to in your car while you're going in a tunnel.

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Originally posted by pkcRAISTLIN your car's user manual should have this in it.

thats what i thought, and i found nothing in there.

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Originally posted by jfk-pilot The reason i'm asking this is because, in airplanes, the manufacturer provides the pilot with certain engine power settings, which in return promise you the pilot a certain amount of gallons per hour being used during cruise and other stages of flight.

Quite possibly because the cruising conditions of airplanes do not vary as erratically as the driving conditions do, and hence can be modeled accurately to predict the engine performance.

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Originally posted by twilightki : It feels like something you'd listen to at 4 in the morning, or listen to in your car while you're going in a tunnel.

wow dude
seriously, stop being so cheap

for SUV's the optimal speed for fuel efficiency is around 90km/h
But in your case you drive a Honda Accord, a fuel efficient car in itself, so If you are worrying about saving $2 at the gas pump, then I recommend you drop the honda and get a smart car
but then again, smart cars aren't cheap
so I would recommend for you a Geo

You'll burn the most fuel when accelerating, especially when accelerating hard, the car has an automatic transmission so it's already taking care of the relative speed-rpm to run at around close to optimal straight from the factory. It's not too much different to a plane with an internal combustion engine except for the fact that they don't have a gearbox as such.

lowest RPM=best gas mileage

I know there was a study that demonstrated that having your tires inflated to a certain psi could affect your gas mileage as well. Less rolling resistance and such.

I've heard one of the best ways to maintain good fuel economy on an automatic is to, every time you come to a complete stop, put the car in nuetral. When you are ready to go again, rev the engine to roughly 5400rpms and then put the car into drive. This helps alleviate the high gas consumption of the engine as it struggles to overcome the inertia of the autombile.

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Originally posted by VAR lowest RPM=best gas mileage

incorrect
to low of RPM produces a "lull" (my term) in a car
anyone who drives standard knows this

if you put your car into 3rd gear at 1500rpm, you engine is not producing the right power to gear ratio and requires a lot more effort and inefficiency to get the car up to the optimal RPM for that gear (3000rpm)

also lets say your on the highway in 5th gear doing 100km/h (maybe 2300 rpm)
and to drop down your RPM to "save on gas" you switch to 6th gear
your now doing 100km/h in 6th gear at roughly 1700rpm
your engine is not efficient at this point and your not saving on gas at all

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Originally posted by ak87 wow dude seriously, stop being so cheap for SUV's the optimal speed for fuel efficiency is around 90km/h But in your case you drive a Honda Accord, a fuel efficient car in itself, so If you are worrying about saving $2 at the gas pump, then I recommend you drop the honda and get a smart car but then again, smart cars aren't cheap so I would recommend for you a Geo

this is not so much about being cheap or saving a couple bucks at the pump, more of just scientific curiosity.

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