Wario's car was simply called "Wario Car" in Mario Kart: Double Dash!!, and was later renamed "Brute" in Mario Kart DS but most people prefer to call it Wario's Pimpmobile. His blinged out ride has been almost as iconic as his bomb-omb fetish since it first appeared in Wario Land 4, one of the first games for the GBA. Since then, most other games that show Wario usually work in his sweet ride whenever possible.
It's quite fitting of Wario's already established 'badass' persona. Wario isn't really a villain Mario so much as he is the Bluto to his Popeye. And as such, Brute really shows off his gruff bully-like demeanor.