At the end of 1978 TVR launched yet another variant on the M-series theme. Following a one-off special 3000 M convertible built for Martin Lilley himself, TVR embarked upon its first convertible project in history. Again, the TVR Convertible or 3000 S was mechanically similar to the 3000 M and Taimar models, sharing the rolling chassis, engine and mechanical components. The 3000 S was also comparable in terms of performances.

The main differences were of course to be found on the body work side. Despite its familiar looks, the Convertible was not merely a 3000 M with chopped-off roof. Apart from the bonnet each body panel was different with special cut-out doors and a redesigned rear section. Hence the 3000 S became the very first TVR to offer a separate boot space. The familiar Consul windscreen was dropped too in favour of a new one with metal surround, while the removable side windows lacked a winding mechanism. The vinyl hood was a genuine soft top foldaway item. As for the interior, the lowered base of the windscreen necessitated a rearrangement of the dashboard lay-out: speedometer and rev-counter moved to each side of the transmission tunnel, placing the speedometer out of the driver's sight on right hand drive cars and the rev-counter out of the driver's sight on left hand drive cars.

Although the 3000 S proved an instant success, production remained once again limited with just 258 cars built in 1978-1979. However the popularity of the Convertible in its short production life showed the shape of things to come for TVR.