As of July 2015, there are 13 racing games featuring Sonic the Hedgehog. The most recent games are "Sonic & Sega All-Stars Racing" and "Sonic & All-Stars Racing Transformed," both developed by Sumo Digital.
The recent Sumo Digital games are mascot kart racers in the style of the "Mario Kart" games and draw characters from Sega's entire library. The first game is solely a kart racer, but characters are able to also fly planes and drive boats in the second game.
Other Sonic racing games include "Sonic Free Riders" for the Xbox 360 with Kinect, the "Sonic Rivals" series for the PlayStation Portable and the "Sonic Riders" games for various consoles.