I know I haven't been getting very good mileage lately, but yesterday I figured it out and I was only get 9 MPG. It's all city driving that I do, mainly just home and to school and it's a very short distance. I usually only drive one or two miles then I turn the car off, then it's one or two miles back home. Right now, I use 87 gas. Would using 93 up my gas mileage? Also, what should my O2 sensors be reading at if I scan the car with Tunercat.

 

Would help a lil but not to where the offset in the ppg would be any diff. Be better for your car though.

 

I dont really know if it will increase gas mileage, I get about 20-21 on the highway with premium.

 

Our cars are *not* designed to run on 87. While you can use it, the engine will not be running at maximum efficiency. With our high compression ratios, the computer will have to take out a lot of timing to prevent preignition and detonation. Also, if I'm not mistaken, may be that your Air/Fuel is a little rich since it will also add more fuel to cool the charge. That could be causing your low gas mileage. Switching to 89 or better 92-94 should help. 87 is for low compression engines. I even use 89 octane in my ram v-10 that calls for 87 octane since I've noticed a little pinging on hot days with 87. The pinging on our cars is not really noticeable since the computer retards timing very quickly so it goes away.

If you run 93 and add an LT4 knock module I think you will see a good improvement in mileage.

 

A car that never reaches full operating temperature will never be fuel efficient.

 

That sounds like it could be the answer since it only takes me 2 minutes to get to school . Also, thanks for the other input everyone. If anyone else has anything to add, please go ahead and do so.

 

The fact you use 87 octane makes me cringe....

 

wait 20 mpg..........how is that.

94lt A4 here
i say highway miles is half of the total..

i get about 12mpg and only use premium
does this sound about right?
or am i doing this cal wrong or is the gas magically leaking??

 

Yeah but octane does improve gas milage a bit, it burns longer which means its acctually doing work throught the piston travel for a long time.