The first one from Citroen (1954) was called hydropneumatic suspension as it used pump-driven hydraulic fluid and small nitrogen-filled bladders at each wheel to absorb road impacts while also offering load-leveling and, eventually, mitigating body roll. The main drawback to the early systems is that the hydraulic fluid could absorb water—and thus rot the system from the inside out. Citroen is now developing a new suspension system called the advanced comfort program. I can’t explain it, but here’s a site from road and track that may help:
https://www.roadandtrack.com/new-cars/car-
rwood
Interesting stuff