Speed Dependent Damping Control (also called SD²C) was an automatic damper system installed on late-1980s and early-1990s Cadillac automobiles. This system firmed up the suspension at 25 mph (40 km/h) and again at 60 mph (97 km/h). The firmest setting was also used when starting from a standstill until 5 mph (8 km/h).
Applications:
Computer Command Ride
The semi-active suspension system was updated as Computer Command Ride in 1991. This new system included acceleration, braking rates, and lateral acceleration to the existing vehicle speed metric.
References
Speed Dependent Damping Control Wikipedia(Text) CC BY-SA