NO RACING IS INVOLVED! TROLLS GO AWAY! YOU KNOW WHO YOU ARE! I have recently installed racing hubcaps and I would like to say I am very pleased. Not only do they look good they also improved my fuel mileage by about 2 mpg! I have ran the hubcaps for one tank so far but I think I have seen an improvement. Before I put them on my average was about 55mpg. After I put them on My millage went up to 57mpg. I finished off my tank today with 59.0mpg on the screen! Of course the temp has been in the 60s the past week but I seen the increase in 40 degree weather when my normal mileage would have been around 55mpg. When I got home from the gas station I looked at my screen and saw 74.3mpg!!! I love the warm temperatures! I cant wait for 80-100 degree heat! I bought the hubcaps from Hubcap Mike. I bought the screw on type because the pop on type will not work on the stock prius wheels. Instead of drilling the wheels like the instructions said to do I decided to make things a lot easier by installing them on to the trim rings. This makes it a lot easier to pop them off encase you need to replace a flat or check your tire pressure. All I did was drill some holes and installed some pop rivets. The stock caps come pre drilled with 3 holes. I suggest drilling 3 more. All the holes will line up perfectly with the flat spots on the trim ring. Make sure when drilling the new holes you make your hole as far away from the outside as possible because you don't want the rivets to rest against the rim of the wheel. When everything is done your car should look like the pictures below. I installed mud guards today and from the looks of it they wont effect my fuel millage at all. The hubcaps stick out enough to push the air around the mud guards.