In 1959, the Maserati 5000 GT was introduced using the chassis of the 3500GT. Two steel-bodied convertible prototypes by Carrozzeria Vignale and Michelotti were developed in 1959 and shown at the Salon de l’Auto in Paris 1959.
The 3500 GT Spyder by Carrozzeria Vignale had 245 units made. It went into production in 1960, as the 3500 GT Convertible or just 3500 GT Spyder, and had a shortened 2,500 mm (98.4 in) chassis weighing 1,380 kg (3,042 lb).
The 3500 GTi was introduced in 1961 as the first fuel-injected Italian production car. It had a Lucas fuel injection (235 bhp). A 5-speed ZF S5-17 gearbox was now standard (3.02:1, 1.85:1, 1.29:1, 1:1, 0.85:1), as well as disc brakes all round. The body had a lowered roofline and became somewhat longer; minor outward changes appeared as well (new grille, rear lights, vent windows). The rather similar Maserati Sebring (3500 GTiS) also a 2+2 coupe entered production in 1962.