The older Citroen models with the hydraulic/pneumatic suspension
The car would "rise" when started, as the engine-driven pump pressurized the hydraulics.
That same hydraulic suspension was tied into the braking system as well. The brake pedal was really a valve which diverted some of this hydraulic pressure to the wheel brake cylinders.
Back in 1967 when the US required that all new cars have a backup/secondary braking system, I understand the way that Citroen met that requirement was that if their primary (or only) system sprung a leak, then the suspension would lower until the tires rubbed on the wheel wells - causing the car to slow to a stop.
Someone can correct me if there are any errors or omissions in my recollection.