[Info-vax] Off-topic follow-up, now with actual data - mileage vs. speed

[JF Mezei]

>> A while back, I think twice even, discussion of gas mileage came up for some 
>> reason. Many here claimed higher speeds get better mileage.

Depends on the engine. Fossil fuel engines are tuned to be most
efficient at a certain RPM.   This is one reason hybrid cars are more
fuel efficient: the generator runs at the fuel engine's most efficient
speed no matter what the car is doing.

Similarly, jet engines now have different speeds for the big fan and the
actual turbine sections so that the turbine can run at the most
efficient speed. A long range aircraft is tuned so that most efficient
fuel efficiency is at cruise speed. Shorter range engines are tuned
differently because the aircraft spends much time at different speeds
(take off, climb, short cruise, and descent).