I have two subs a 97 and an 02, the 97 does better on fuel then the 01. Both are two wheel drive, I felt the newer one should do a little better but not so. My thinking leads me back to when I had installed wider but the same size in diameter tires on a truck I had quite a few years back, the gas mileage went into the crapper. I am thinking about trying to find narrower rims and tires for the new one, the wide tires are worse in the rain and snow then the narrower ones on the old sub. True they look good but in fact are not as trust worthy in bad conditions. Anyone else swapped to narrow rubber??