My powerband in my old 88 Dodge Shadow is around 3500rpm. 3500rpm in 3rd gear is around 80mph. Powerband is where you're going to save the most amount of gas.

I just got a 99 BMW M3 friday. I'll have to see how much gas that gets on the highway. It has a MPG gauge.

Originally posted by Tom_Proctor
My powerband in my old 88 Dodge Shadow is around 3500rpm. 3500rpm in 3rd gear is around 80mph. Powerband is where you're going to save the most amount of gas.

I just got a 99 BMW M3 friday. I'll have to see how much gas that gets on the highway. It has a MPG gauge.

I have to be honest with you, your statement is incorrect. The lower your rpm the better fuel economy. The lower the speed the lower the wind resistance. These are the keys of saving fuel on the highway. Also, I've never heard of anyone speeding to save fuel. Usually people speed to save time not money.

It is true that your engine is efficient while in your power band zone. That just gives you the bang for your buck if you want power. If you want better fuel economy then you lower your RPM...

With the hurricane in full force, I think its time for everyone to drive more sensible. Who knows how much gas will peak at if any of the refineries are damaged...

Sorry guys but i had to butt in on this discussion. I am currently training to become an Airframe & Powerplant mechanic. In terms of fuel efficency in a powerplant (engine or motor) you must take a few factors into consideration.

1. Weight

2. Rolling Resistance

3. Air Resistance

4. Driving characteristics

5. Engine displacement (the amount of Fuel-Air mixture your engine uses every time the crankshaft makes two revolutions.)

6. Engine Weight

7. Frame Weight

8. Useful Load (Passangers,Cargo,Fuel, and the Driver.)

9. Quality Of Maintenance

10.The Richness Of The Fuel-Air Mixture (a ratio that compares fuel to air in a fuel-air charge.)

Now taking these into consideration we can come up with some guidelines.
Your fuel metering system(carburetor or fuel injection.) Uses a richer mixture when you use more power in the form of accelerating. This uses more fuel. Gasoline weighs 6 pounds per gallon. For a 15 gallon tank thats 90 pounds almost like having an extra person. Dont get a full tank when you fill up. the more your tires flex and the less round they are the more energy you waste trying to roll a car on squares. Get stiff, low rolling resistance tires and keep them inflated. If you can afford it you should replace your car's body with carbon fiber paneling its stronger than steel and very light. Get a smaller engine. Large engines with a bigger block size and more cubic centimeters of piston displacement use more fuel. Try for an aluminum engine as opposed to a steel one because aluminum is lighter. One last word. The grade of gas affects its anti-detonation (anti-knock) properties only! A higher grade of gas has the same amount of chemical energy (about 20,000 BTU's per gallon) as a lower grade. Get the lowest grade your engine will run on.