I recently went to the High Sierra's (elevation 8-10,000 feet) and my gas mileage was holding at 18-23 mpg will all my jeeping and driving to Reno too. In Southern Calif, I get only 12-13 mpg even on the freeway. I have a HEAVY Rubion 4-door with 513 gears (only 32" wheels).

Any way to adjust the air/fuel mixture on a 2008 Rubicon?

Any suggestions would be appreciated.

Thanks...

 

Just a thought - could be gas mixtures. The stuff from Cali cities is heavy on additives that hurt mileage and economy.

 

Thinking the same thing. In Houston I get between 13-16 mpg. This summer in CO I was getting 18-20, including in 4L on trails. We have to put so much crap in the gas to make it burn clean it destroys mileage.

 

take a look at the E% next time you fill up. I was at a gas station that had E15 instead of the E10.

but most likely, it's the benefit of higher altitude, from a write-up I clipped a while back - not my work:
Altitude decreases an engine’s octane requirements because of the change in air pressure. The higher elevations have a lower level of air pressure, which means an engine needs less octane to properly fire due to the lower ambient pressure = less fuel burns, which means the overall fuel-per-mile efficiency is increased because the engine is working at a reduced compression rate.

 

i live at sea level and any time i go to high elevation i always get alot better fuel milage