I tried looking for some before and after numbers but it seems like hardly anyone wants to put a set of rims on that cost about as much as the car. I would think it would make it get a few more mpg and probably shave a little time off the 0-60 but can't find anything really concrete. I'm going to be having two sets of tires for my Insight anyways most likely so if I'm going with a second set of rims I might as well get something that looks a little better and adds performance. If they don't really add performance I might get Kosei rims.