The Hispano-Suiza H6’s exhaust-powered servo brake system of 1919 was so sophisticated that it made competing manufacturers’ brakes seem primitive by comparison, yet the technology completely vanished when hydraulic brakes standardized in the 1930s, making it one of automotive history’s most forgotten innovations that wouldn’t be reinvented in spirit until power-assisted braking became universal decades later.
Car Fact #59 — August 14, 2026
