Just throwing out random stuff:

- Oil overfilled by the dealer? That could kill the oxygen sensor and send the EFI into rich mode.

- E-brake servo/wheel bearing going bad? Jack up the back of the car and make sure the wheels are spinning freely.

- Did someone accidentally put E85 into the car? That would cause a 25% drop in fuel economy.

 

oil level seams ok. if the paking brake servo were having issues would'nt there be tell tail sighns?o2 sensor would there be a code? or code only upon failure and not out of range?

 

It could be your driving habbits. Short trips, hard acceleration, 20 mpg is feasible. Try 20miles of steady highway driving on flat roads with cruise at 70 mpg, . Reset the average fuel consumption when you start, that should net you about 32 mpg per your average fuel consumption readout

 

does it always say 21 mpg or does it change? If there is a number 2 in the display it will show over all comsumption and not a single trip you just took. Maybe tht helps?

 

I just finished my first full tank and barely reached 20 mpg. Its an 07 2.0t with 45k. I have a strong suspicion that the dealer did not put the right oil in. anyway to tell?

 

oil viscosity would have no impact on your gas mileage