Maserati's chief engineer Giulio Alfieri developed the two 2+2 prototype 3500GT, revealed at the Salon International de l'Auto in Geneva, March 1957. Both had a 2,600 mm (102.4 in) wheelbase and aluminum bodywork; one a superleggera body by Carrozzeria Touring of Milan, the other by Carrozzeria Allemano. The design incorporated

Maserati 350S-derived straight-six cylinder, DOHC 3485 cc litre 42 DCOE Weber carburetor engine (220 bhp at 5500 rpm),
mechanical Magneti-Marelli ignition, dual spark plugs and dual fuelpump
4-speed ZF S4-17 gearbox (2.98:1, 1.99:1, 1.34:1, 1:1),
Girling 12" turbofinned drum brakes front and rear
Borg & Beck-made single-plate dry clutch,
live rear axle, differential (mechanics) by Salisbury,
suspension by Alford & Alder: Front wishbone and coil-springed suspension; rear semielliptic springs.
16" steel wheels with 6.5" Pirelli Cinturato diagonal tires.