On fuel economy, the 996.1 3.4L should get roughly City13.7 Hwy 27.7 mpg (US gallons). The 996.2 3.6L should get 14.4 City 27.7 Hwy mpg (US gallons). That's not too bad in the grand scheme. You might consider getting the ECU reflashed if the fuel economy bothers you. Worst case, you'll have a much quicker car!