I've bought a used 2013 XC70. I'm going to have a towbar fitted to tow a 1600 kg caravan. The handbook mentions who optional extras that are fitted to some cars that would be useful for towing a caravan: Trailer Stability Assist and Self-Levelling Suspension. How can I tell if these are fitted to my car? I'd heard about Self-Levelling Suspension before I bought the car so I asked the dealer. He checked it out and said the car does have it. But how do I know he's right?