Never thought I'd talk about cars here but I never said the characters on this world had to be living.

The Buff is Bean Bandit's custom ride in which he does the most jobs in.
According to some sources, the car is a Porsche chassis with a Corvette Stingray Engine block with clear inspiration from the Ford RS200.
It's crazier specs include four Wheel drive, four wheel steering, 300kph speed, excess of 730hp, bulletproof glass, armoured battleship plating to make it pretty much indestructible, bladed braking system and ability to drive sideways, the only thing missing is nitro.
Kenichi Sonoda, Riding Bean's creator suggests that everything on Buff is capable in real life when the OVA was released with the exception of the bladed braking system, a testament to his attention to detail regarding guns and American cars.
In reality, it's quite a Frankenstein creation combining a Porsche 928, a 3rd generation Chevy Camaro and a MKIV Toyota Supra, also considering the weight of Battleship armour plating, it's fuel economy must make the Hummer look like an eco car in comparison, I'm also not buying that it can do 300kph.
So that's Bean Bandit's car, terrible car in real life but an absolute beast in the anime and manga.