I've been trying to figure out where to start with this whole thing...
My gas mileage went from 30mpg highway to 21.8mpg. Here's the changes to my car in the last year...
1) 18x8 tires and new rims. The MSR 045's are 4 pounds heavier than my Comp G rims.
2) LIM replacement done by dealership JUST before I had to move from Idaho to Virginia. Never noticed any issues with the engine running odd. Maybe I'm an idiot? Extremely poor timing right before my move too.
3) I noticed my a/c compressor is going out. Perhaps it's adding some drag to the serpentine? I don't see how it could unless the clutch is engaged. When I run my a/c my mileage drops more.
4) Change in elevation from 3000' to -1' due to move
5) I had to start using 10% ethanol since my move to VA. In Idaho I was using 100% gas.
*scratches head* I don't know where to start looking :/
