Here is my first attempt at racing with a Mercedes in Mario Kart 8. He uses the W 25 Silver Arrow, the Mercedes GLA wheels, MKTV glider, driven by a yellow Yoshi. It handled pretty well, but the speed was not where I would like it. Also, something I noticed was that I needed to restart the game after downloading/installing the new karts and characters, but I don’t recall ever reading that I needed to do that. So, if you are having issues finding them, try restarting the game.