1. Mario Kart is meant to be a party racing game that is fun. It should not be of the same sorts as Forza or GT5, etc... It is more about the skill and less about the karts regardless.
2. No karts(Or bikes or ATV) are meant to be reliably true to real life. There is no point of having stats.
3. In Mario Kart 8 Dx, the best looking karts and wheels are often avoided by Pro gamers and competition usuals. Instead, the best wheels are rollers which look f***ing ridiculous and the best karts/bikes are the biddy buggy, day tripper, Mr.scooty, etc, all of them don't look fast yet they function better than the Circuit Special and the Mercedes GLA. If you gotta make the stats, at least make it make sense. Again, since it is not meant to be a serious racing game whatsoever, people should choose whatever vehicle they like without analyzing its effects.
4. In Mario Kart Wii, you won't see dry bones without a Bullet Bike, and that is rare compared to Funky Kong with the Flame Runner. About 90% of all uses this combo. You literally don't see Mario with the Day Tripper, nor a Dry Bowser with the Jet setter(Well unless the user is trying to challenge himself, and that is extremely rare). Having stats means people are prioritizing some stats over others, and this will make the rooms monotonous consider there will be vehicles better than others. Then more than 50% of the choices will go to waste consider they don't spike at the most desirable stats.