Quick question,
If I was traveling between 10-50 miles would I save more gas by going 60 and having a lower RPM or by going 75 and getting there quicker? I have a stock jk.

 

Lower RPMs will result in better MPG.

 

Wind resistance is your enemy. The faster you go the more wind resistance which kills MPG.

 

its actually a combination of both, the highest efficiency of a car engine is around 55, less will reduce it by friction and more will reduce it by wind. try to keep both speed and rpm stable. do not acelerate up hill and take advantage on down slopes with out increasing speed to much

 

That may be true if the efficiency you refer to includes time and not just mpg.
In the OP's question, he will burn less gas over the same route if he goes 60 mph instead of 75 mph. He'll burn even less gas if he goes 40 mph over the same route.

When talking about efficiency, the typical car engine is most efficient when nearly fully loaded at wide open throttle. It's getting the most usable power out of the gasoline consumed. The simple mpg's will be very bad, though.

 

that is true, however, i was assuming he is just driving and trying to save gas, this way you need to consider time, distance and fuel used. less speed is not necessarily better.

 

Technically speaking, the lowest rpm at the peak torque provides the best mpg. The down side? When that rpm is high in the engines natural range and it's mated to a brick.