Nintendo officially announced some new DLC packs coming to Mario Kart 8 this November and May 2015. These two packs will add a combined total of 16 new tracks, new drivers, and new karts.

Starting August 27, you will be able to pre-purchase the DLC for $7.99 (USD) each or $11.99 for both packs. These packs are theme focused with the first being Legend of Zelda themed and the other being Animal Crossing themed.
Pack 1: The Legend of Zelda X Mario Kart 8 (Release Date: November 2014) - $7.99Pack 2: Animal Crossing X Mario Kart 8 (Release Date: May 2015) - $7.99Pack 1 + Pack 2 Bundle - $11.99