Asset:
-a useful or valuable thing, person, or quality
-property owned by a person or comany, regarded as having value and available to meet debts, commitments, or legacies

If I were to default on a loan the bank could take my car as collateral. If my net worth were calculated, the value of my car would be included. A vehicle is an asset if you own it and a liability if you loan it.

As for collecting cars.. I would love a full garage of exotic luxury cars! That would be a dream come true :D My boss had that that same S8 but had to downgrade to an A8L as it was too much power for him... V10 vs V8 (he 75 years old). Awesome car regardless of the engine tho congrats!