PThe second series of the Biturbo S was introduced in 1985, with some minor upgrades, and was therefore known as the Biturbo S II.
A slight increase in power output improved the acceleration figures, whilst the more voluminous fuel tank allowed for a greater travel autonomy. 1038 cars were produced, combining the 1st and 2nd series.
Introduced in 1984, the export version of the Biturbo S was fitted with the upgraded 2.5-litre unit instead of the 2.0-litre engine available only in Italy. It was sometimes referred to as Biturbo ES, where the “E” simply meant “Export”.
Other than the modifications linked to the engine upgrade, the Biturbo ES was similar to the Biturbo S, with two-tone paint and blacked-out chrome trim. The power output was 196 hp, 16 hp more than the Biturbo but 9 hp less than the Italian 2-litre Biturbo S, because of the catalyser fitted to match American regulations.