Confirming earlier reports, Nintendo’s amiibo figures will be compatible with the excellent Mario Kart 8 as well as Super Smash Bros for Wii U and 3DS.
When you scan your particular character’s amiibo into the game, you’ll automatically unlock a costume to its corresponding character for your mii. So if you scan a Samus amiibo, you’ll get a special Samus Aran racing suit for your amiibo. Ten amiibos will be compatible (so far) for Mario Kart 8 including: Mario, Luigi, Peach, Capt. Falcon, Samus Aran, Yoshi, Fox, Link, Donkey Kong and Zelda.
Here is an image of the racing suits below: