'Racing has played a major part in the development of all Aston Martin engines since Frank Halford designed the original 1.5-litre unit for Bamford & Martin. The 3,995cc 6-cylinder light alloy engine fitted to the DB5 is in all major respects the same as that which powered the 4-litre prototype which ran in the 1962 and 1963 Le Mans 24-Hour races.' Autocar, 21st May 1965.
Aston Martin's post-war evolution took a giant step forward with the launch of the DB4 in 1958. Classically proportioned, the Carrozzeria Touring-designed body established an instantly recognisable look that would stand the marque in good stead until 1970. The engine was still an all-alloy, twin-overhead-camshaft, six but the old W O Bentley supervised 3.0-litre unit had been superseded by a new design by Tadek Marek. The new 3,670cc engine featured 'square' bore and stroke dimensions of 92mm, and developed its maximum power of 240bhp at 5,500rpm. The David Brown gearbox was a new four-speed all-synchrome