I own a Caddy, An SLS and nothing drives like a caddy. NO MATTER WHAT! Doen bimmer or Mercades have AIR RIDE?!?!?!?! NO! only caddys have RSS (road sensing suspension) and air ride. Owned
Actually the Cadillacs don't have "air ride". They have magna-ride. It's a General Motors invention (and a good one!). It's a shock absorber with metal particles in the shock absorber fluid. When an electric charge is sent through the shock absorber, it makes the metal particles align which makes them flow through the shock more slowly which equates to a firmer ride. The suspension rates can be changed on a wheel-by-wheel basis and can be modulated faster than any other active suspension on the road.
I rented an SLS once, and I have to say I was quite impressed by the ride quality. Now if they could just get their build quality up, improve the quality of the interior materials so that they don't look like Chevy's, and make them more attractive, they might have something! In all fairness, though, I do think that GM has been making great efforts with Cadillac. It's the only American brand I actually would consider comparing to the Germans (they're still not quite there, but they're getting closer and closer).