98 camry 4cyl w/140m miles-hi speed or low the mpg stays the same-why?

The hypothesis back in 1974 was based on CARBURETION, less aerodynamic bodies, and bigger engines that were geared for more RPM's at 60 mph. But now ... slowing down 10 mph doesn't really mean much in a passenger car.

Did you fill up at the same gas pump where you started? If not, run through a couple of tankfuls and average the results to confirm. Other variables could cancel out a small difference, like driving style. You'd have to be on cruise control at both speeds to really double check.

i remeber newton:if the volecity(speed)increases there must be an increase in energy consumed(gas). I can't fathom the fact that you can go 10 mph faster on the same amount of gas. I get my gas at the same discounter all the time. I used the a/c but this would have lowered the mileage. The mileage i get is 25-26 mph in city/county driving without a/c. I am the only driver.I had better take physics again. Getting suicidal.

How hard you accelerate is more important than your cruising speed (within reason), because dragging all that mass up to speed quickly uses much more gas than just maintaining 65mph as opposed to 60. I have a '95 4 cyl LE automatic, and get 27 (worst case, Winter) to 34 (best case, Summer) MPG *average* per tankful. The trick is to accelerate gently, coast when you can, and ease up a little when climbing hills or grades. I cruise at 60-65mph, BTW.