Which 1919 automobile introduced the first production servo-assisted braking system?

The 1919 Hispano-Suiza H6 introduced the first production servo-assisted braking system.

Hispano-Suiza presented the H6 at the 1919 Paris Motor Show. The luxury car used a mechanically powered braking servo, derived from technology associated with the company’s aircraft-engine work, to reduce the pedal effort needed to slow its large and heavy chassis. The system operated the brakes on all four wheels.

At a time when many cars relied on relatively demanding mechanical controls, servo assistance was a major advance in drivability. The H6 also gained a reputation for engineering sophistication through its overhead-camshaft inline-six engine, advanced for a luxury car of the period.

This early servo should not be confused with modern hydraulic vacuum boosters. It was a mechanical assistance system, and its purpose was the same basic one: amplify the driver’s braking force. Four-wheel brakes themselves were already appearing on other cars, so the H6’s distinction specifically concerns production brake assistance.