With a capacity of 7.1 litres, and a declared output of 150bhp (Rolls-Royce never dared to reveal their own peak figures, which were not impressive), this provided a huge, silent, power unit with more torque, which was ideal for the powering of massive limousines and (occasional) fast sporting models. Lever-type hydraulic dampers were standardised, and a vacuum servo was definitely needed to help power up the four-wheel drum brakes.
Naturally, there was no power-assistance for the steering (such systems had not yet been invented), so the chauffeur had a hard job. Later models, at least, were available with Daimler’s new pre-selector/fluid-flywheel transmission, which made them even smoother than before. The cars were front-engined and rear-wheel drive with a separate chassis. The engines had an undraught Daimler carburettor on each bank.
The typical Double Six ‘50’ had a lofty limousine body, which could seat up to seven people, might weigh 6,200 lb/2,812 kg, and would cost around £2,500 – definitely Rolls-Royce levels. Not surprisingly, this model was popular with the British royal family, who purchased several, over the years. Fuel consumption could be worse than 10 mpg, but no-one seemed to worry about that. Depending on the body fitted, the car could reach up to 80mph.
To expand the range in 1928, the ‘50’ was joined by the Double Six ‘30’, which had an altogether different and smaller 3.8-litre V12; this model itself was replaced by the 5.3-litre ‘30/40’ in 1930.
Even without the effects of the Depression, Double Six sales would always have been low, but economic problems hurt their prospects further, so the programme was gradually run down during the early 1930s, and the cars were eventually replaced with conventional straight-eight cylinder/poppet-valve cars. Less than 500 Double Six cars were built in the 1920s, even fewer after that.