I own a r56 with 23k miles on it. Ever since I've owned it it gotten an anverage mpg of 30 in all types of driving conditions. I added a cai. Still 30. I added a Riss racing exhaust and it drops down to 22. Take of Riss and put stock back on and it stayed at 22. I recently added a m7 scoop and still at 22. Not sure what caused the drop. Any ideas on getting it back to 30?

 

maybe a bad 02 sensor.

 

I had a similar situation where all of a sudden i was getting 20 mpg instead of 31. Turned out one of my brake calipers froze up and was slightly dragging my rear wheel.

 

Wouldn't I get a warning light for the bad O2? And how did you find out about the froze caliper? Did you smell sonething burning or?

 

Not necessarily..........they just simply go bad but your car would probably be running like crap if it was the O2 sensor. Happened on our 05 and the car was hesitating and losing power, but no odd smells.

 

You can test the brake easily enough. Release the parking brake and see if you can push the car. Or, jack up the rear and see if the wheels can be turned by hand.

 

no, just the drop in MGP. It was complete frozen, just not releasing all the way. I brough it to the dealer a few days after i filled up and noticed the drop in MGP.

 

I noticed a drop in MPG recently...but mine is probably different.

Generall my MFA will show 32-34 MPG in the city (just a turboback from ALTA installed). After installing my ALTA Intake, I noticed my MPG is now at like 30-28 in the city. I assume thats pretty normal?