I have a 2017 Prius eco, and it has 18in trd wheels installed! For a while I noticed my sub-par mpg avg of about 40. A ton of people immediately told me it was because of my not stock wheels! I was ABOUT to replace them, until I realized I had an axle issue (see. clicking break thread) so I went in to get that fixed. After this, I’m now averaging around 49/50 in a pretty hilly/highway-y place I know that's not great for a gen4, but I'm happy with the look and performance of my car now.
