The B Dasher is one of Mario's special karts in Mario Kart DS. While certainly not the most popular choice among gamers, it is unarguably the best known seeing that it was the feature vehicle on the game's box art. It's a sleek car with red racing stripes and a classic Mario "M" in front, indicating that this is his vehicle.
B Dasher also appeared in Mario Kart 7. It can be unlocked by getting right amount of Coins. It is completely same. Not just Mario and Daisy can use this, but also other characters along with Mii can use this. Their badge or sign changes.
In Mario Kart 8, it was included in the first DLC pack as among its 4 vehicles.