Proto P2 cars are a kind of racing karts with a closed body and very light weight. They are driven by motorcycle engines which makes them very maneuverable and suitable for slalom racing and for tiny and small circuits.
They are usually made by enthusiasts, but there are specialized companies. For example, Polini Motorsport. They equipped this tiny Fiat 126 with a modified Honda 1000cc engine taken from the old CBR 1000RR superbile.
Watch it racing at Castelletto di Branduzzo circuit during the 2018 Challenge del Lupo!