This engine, considered advanced for its time due to its hemispherical combustion chambers and very short inlet and exhaust ports, develops 80 horsepower[2] at 4,500 rpm, and gives the car a top speed of about 148 km/h (92 mph),[2] with acceleration to match.

Owners soon found that setting and maintaining the numerous clearances in the system was difficult, but vital to keep the engine in tune.

It has all flat glass, apart from the curved rear window, which is glazed in Perspex, and was available to specification with a top hinge.

This was very welcome on warmer climate export markets, where the sliding door windows provided only marginal ventilation to the occupants.

In later 400s the spare wheel is mounted on the rear hinged boot lid, inside an aluminium cover.