Call me crazy, but I actually love the look of 18" wheels on these cars ... AKA, police interceptors look amazing to me when they're clean with some tire shine on them. If I do wind up getting an ST, I may look to go this route, though not with the same wheels. Handling might suffer, but ride will improve and tires themselves will be cheaper, at least compared to the 21" wheels. Surprisingly, the price difference between the 20" and 18" tires are pretty similar, but I'm sure there will be weight savings.