The P538 or P538S was a rear-engined race car launched in late 1965 or early 1966 by Scuderia Bizzarrini of Livorno, Italy.

That car crashed during tests and the history ended right there, because the chassis was cut up.

It was entered as a Sport Prototype (unsuccessfully) as open cars were banned from Le Mans.

Then there is the white closed P538 Duca d' Aosta with chassis number # 262 974, but that car never had a spider body.

[2] P538-003 debuted at Le Mans in 1966 with starting number #10 with Swiss driver Edgar Berney taking the first stint.

A second team in a production-based Bizzarrini A3/C with starting number #11 with chassis number # BA4*106, driven by Sam Posey and Massimo Natili, was disqualified after a pit lane violation, possibly while returning with serious frame damage.

Amongst those building the cars, was former Bizzarrini engineer Salvatore Diomante at Autocostruzione SD, Torino.