Two rules. The fundamental design was laid down by Robert Eberan-Eberhorst, one of the world's leading theorists of racing car design, who had replaced Ferdinand Porsche at Auto Union and designed the Auto Union Type D Grand Prix car. His protégé and successor David Hodkin completed the G-Type design. The frame was constructed of two longitudinal magnesium tubes with four crossmembers. Suspension was by double wishbone with coil springs at the front and de Dion tube at the rear. The car was powered by a Bristol engine with modifications to Hodkin's specifications. Stirling Moss drove, but the engine was unreliable and the race results were disappointing. Moss said: "It was, above all, a project which made an awful lot of fuss about doing very little. By this time I was very disillusioned by the Clever Professor approach to racing car design. I would eventually learn that even the most brilliant concept could fail if the team concerned lacks the manpower and organization and money to develop the inevitable bugs out of it." Johnson sold the project to Bristol—who used the car as the basis for an assault on Le Mans that would bring them several class wins in the mid-1950s—and focused the company on research and development (R&D) engineering. He eventually sold it to Zenith Carburettor Ltd, which was then purchased by Solex, another carburettor firm. Chassis design for the Jowett Jupiter In 1949 von Eberhorst, working for ERA, designed the space-frame chassis for the Jowett Jupiter. Legacy Although renamed Engineering Research and Application Ltd, and still primarily an R&D operation, ERA still did a small amount of race preparation. In the 1980s it put its name to the ERA Mini Turbo, a turbocharged version of the Mini. Today ERAs in competition The vast majority of prewar ERAs are still in existence, and they have continuous and verifiable provenance. They still compete in historic events despite the youngest being nearly seventy years old. The cars are particularly associated with the Shelsley Walsh hillclimb thanks in large part to Mays, who won the first two British Hill Climb Championships in 1947 and 1948; indeed an ERA has for many years held the hill record for a prewar car. Mays exhibition There is a permanent exhibition about Raymond Mays' contribution to motor racing, including his ERA days, at Bourne Civic Society's heritage centre in Bourne. It is open on weekend and bank