The second series Biturbo was referred to as Biturbo II on the official Maserati documentation. Introduced in July 1985, it maintained the same exact characteristics as the first series, save for the adoption of Nigusil cylinder liners, a larger fuel tank, and a Sensitork differential in place of the Salisbury-type previously mounted.
Nigusil was a galvanised aluminium derivate brevetted by Moto Guzzi, which permitted the use of aluminium for both pistons and liners, thus allowing for a parallel dilatation of the two elements at all temperatures. This produced a great reduction in tolerance figures and engine temperature, improving smoothness, noise levels and oil consumption.
Externally, the new series could be identified by the new 6″ J x 14″ alloy wheels shod with Michelin MXV 195/60 VR 14 tyres. The total of 9206 units produced refers to the 1st and 2nd series combined.
The 2.5-litre export version of the Biturbo was also revised in July 1985, albeit with few modifications. Just like its 2.0-litre counterpart, it became equipped with Nigusil cylinder liners and a Sensitork differential in place of the Salisbury-type previously mounted.