There are quite a few bodies you can unlock for your kart in in Mario Kart 7 for the Nintendo 3DS, which are unlocked by collecting coins in Grand Prix mode.
Here are the bodies you can unlock, and how many coins you need to collect to unlock them.
Kart bodies appear in random, but here are the kart bodies that are available in the game.
Unlockable Kart Bodies With Coins
B Dasher Body
Barrel Train Body
Blue Seven Body
Bumble V Body
Cloud 9 Body
Egg 1 Body
Koopa Clown Body
Pipe Frame Body
Tiny Tug Body
Unlockable Kart Bodies Through Other Methods
Golden Standard Body - Get a VR higher than 10,000 points, or collect 20,000 coins
Check out my other guide if you’re looking for the full list of unlockable kart parts in Mario Kart 7.