Later versions of the coupé and cabriolet bodied Glas GT were also powered, in some cases, by the same engine as the saloon.

[3] Not for the first time with a new model from Glas, the car introduced at the 1963 Frankfurt Motor Show was far from ready for volume production.

By now series production had started, in August 1964, following the annual holiday shutdown, although volumes were still constrained by lack of cash for investment.

A year later, in September 1965, claimed power from the standard engine increased further to 85 PS (63 kW) at 4900 rpm and the maximum speed to 155 km/h (96 mph).

The compression ratio increased in the configuration from the standard car's 8.5:1 to 9.5:1 or 9.7:1, suggesting the manufacturer was taking advantage of the wider availability of higher octane fuels which was a feature of motoring in much of western Europe at this time.

Glas were never able to afford the investment in production facilities and a dealership network that would have enabled the car to compete on level terms with the Opel Rekord or the BMW 1800/2000.