Rolls-Royce must have been fuming by the buzz that surrounded the launch of the Hispano-Suiza H6 at the 1919 Paris Salon. For such a large luxury car, the new model – designed by the brilliant Swiss engineer Marc Birkigt – not only looked imposing, but also bristled with innovative features. The firm’s aero experience was clearly evident in this vintage exotic. Under the long bonnet, the all-alloy 6.6-litre straight-six, finished in signature gloss-black paint, was in effect one bank of Hispano’s magnificent V12 aero engine, with its overhead camshaft driven by a vertical shaft following aviation practice.
Just one twin-choke updraught Solex served the engine, mixing fuel with air warmed by the crankcase. Twin-plug ignition and Hispano’s patented threaded-cap valve stems both featured in this handsome, compact unit, which would have impressed even Ettore Bugatti. The auxiliaries were kept hidden, like servants in a grand château, and the crankcase was stretched wide to meet the chassis sides and make the engine bay even tidier. Peak power was 134bhp at 2750rpm, with maximum permitted revs at 3000, but some reports claimed that the factory was over-optimistic and 115bhp was closer to the truth. Whichever way, the power output was huge compared to rivals, with Rolls-Royce mustering around 70bhp and Isotta Fraschini about 80.
When most makers were still boasting of having four-wheel brakes, Hispano was far ahead of the game with its servo assistance integrated with the gearbox, a design patent that Rolls-Royce carried through to the 1965 Silver Cloud. The conventional deep-channel chassis was well braced by a finely cast aluminium bulkhead.
Sporting motorists at the Paris show may have scoffed at the three-speed ’box but Hispano, like many quality firms, regarded gearchanging as an operation unfit for gentlemen, and claimed that the engine’s torque would provide ‘smooth and flexible’ performance whatever the route. Frustratingly, pre-war road testers didn’t report torque figures but the H6B was reckoned to give 350lb ft at just 1600rpm. No wonder it could accelerate in top from single figures to 60mph in just 30 secs. The H6B’s pace clearly matched its impressive stopping power, which all underlined its bold claim to be ‘the best car in the world’.