What is more efficient for driving a 90 mile trip?

[Kal-El]

He does bring up an interesting point that I've always thought about.

Going 55 will keep the engine running for approximately 26 minutes longer, thus burning fuel 26 minutes longer than if he drives 75. So the conundrum is finding out if the added wind resistance of going faster actually adds so much more work for the engine that it burns more fuel in 72 minutes than in 98 minutes.

[talnlnky]

Originally Posted by Kal-El

He does bring up an interesting point that I've always thought about.

Going 55 will keep the engine running for approximately 26 minutes longer, thus burning fuel 26 minutes longer than if he drives 75. So the conundrum is finding out if the added wind resistance of going faster actually adds so much more work for the engine that it burns more fuel in 72 minutes than in 98 minutes.

I've thought about this too... and I think you only really improve the
"gallons per trip" by going faster when talking about slow speeds, say 25 or 35.

The difference in times at slower speeds is MUCH bigger than it is at high speeds. difference between 20 & 40 is a factor of 2. Difference between 50 & 75 is only 1.25.

but with slower speeds its really hard to tell if you get better mpg's due to time decreases, or if it is other factors... like different gears.

Another reason why I think faster speeds don't allow for better gallons per trip.'s by going highway speeds you now have a drastically increasing air resistance to battle, thus reducing efficiency.