This has just reminded me that as a kid I used to nag my parents to visit car dealerships and collect car brochures. My parents were too risk averse to buy anything like a Citroen, but they were clearly the most forward thinking company. I remember the Citroen XM being the most futuristic car I'd ever read about, but now the cheapest hatchback has far more advanced technology!
Even in the 1990s, a Xantia would be a cheap way to buy a luxury suspension. Still amazes me that my '74 DS and my '98 Xantia can use the same hydraulic fluid. Even the pressure spheres are interchangeable, although not advisable.
The Xantia probably has the best of the hydraulic suspension systems that were ever on the market (including MB, which is a ridiculously fragile system). The XM is more comfy but the Xantia is far more reliable mostly because it is a somewhat simpler system (cheaper car, so less complexity = more profit but incidentally also more reliability).
The very worst was the SM, which overcomplicated just about everything. If you open the hood on one you'll have at least six "WHY?"'s going through your head at once, the kicker being the rotating shaft over the top of the engine to drive a pump on the other side of the block.
The Xantia can have the classic hydraulic suspension (hydropneumatique) identical to the Citroën BX or the Hydractive II system with an electronic calculator on board and more "spheres". The XM had the first Hydractive system.
