Whereas the 603 was a dramatically restyled version of the characteristic Bristol two-door saloon, the 412 was different in that it was a Targa-type convertible with a removable roof that could be placed in the large luggage compartment.

[3] Other changes included improved ventilation, redesigned seats, as fitted to the 603, and service intervals extended to 10,000 miles (16,000 km).

[3] In an effort to move into the United States market, Bristol designed a 412USA that complied with the extremely strict emissions and safety regulations of the US, with a catalytic converter and a much stronger roll bar than on the first 412.

However, the 5,899 cc V8 engine was upgraded by the addition of a Rotomaster turbocharger which increased power and torque by approximately 30%, giving the Beaufighter a maximum speed of 241 km/h (150 mph).

To cope with the extra torque, the Torqueflite automatic gearbox that had been a constant in every Bristol since the 407 was upgraded with a stronger, thicker propeller shaft and a torque converter taken from the 7.2 litre (440 cubic inch) RB engine found in Chrysler's top-of-the-line models during the 1970s.