i have no clue, but if someone wants to reference, ive clocked my car with 2.83 rear gears while beating the crap out of my car for the last two tanks of gas (problems with the girl means ive been angry and late often, lol) and i got 18.9 and 19.6 MPG, all city miles... and i have clocked 24.7 and 25.8 highway MPG, so either way, these GT's arent too bad i guess in pretty much stock form...