Thanks to all who replied to my post! No sooner had I posted the note, I had to go on a trip and could not reply!! I did replace my stock airfilter with a "Eurosport" washable high flow air filter. Please let me know what you think! Anywho, I have about 3-4 questions which I will post separately so I will start with a tire/fuel economy question. I have no highway mileage figures as of yet, but I do have some somewhat dismal city mileage figures (which I know can vary wildly!!) I am getting between 17-18 mpg while my wife's XC70 AWD gets 20/21mpg. I'm thinking, her car is heavier, less aerodynamic and sits higher off the ground but has a slightly small engine. My S60 is lighter, more aerodynamic but I think has a bigger engine. Both these mileage figures are from each cars trip computer...are they even comparable??? THEN I REMEMBERED....I don't have the stock wheels and tires for this S60!!!! The car was to be sold with a stock 235/45/17 set of wheels, but the wheels were scratched and the tire were a bit worn. I told the Volvo sales guy, I don't want this setup! I will buy the car if it has a good set of 16" tires/wheels. What I got was a brand new set of 16" Michelin Primacy MXV4's and much cleaner wheels. I thought that they would be the same size but according to the Miata tire calculator there is a bit of a difference! Sooooooo my question is, how does this affect my gas mileage as far as the trip computer goes???Am I actually getting a bit more MPG than the trip computer reads???? Thanks, Bill PS. I think I mentioned that the car has 34K, runs great!

 

I think you just have a much heavier foot than your wife. I have a 2.5T too and although it is a FWD (The AWD has a little less mpg) it has the IPD ECU upgrade so I would think that in term of fuel consumption it should be pretty close to your AWD. If I drive with a heavy foot I easily get to the same range as you in town and even less otherwise I usually get around 20/21mpg downtown. On the highway though and at a stabilized speed of 65/70mph I average around 29/31mpg. I suggest you try your car on highway and see what your MPG is before looking at something wrong with the car.