I cant really determine if you should or not cause several factors come into play, and we dont know how much you mom is willing to spend, and more. Anyway BMW reliability is exceptional.
It's an Audi so the build quality should be fairly high, its quite a high spec model so its going to be quite expensive and will depreciate in value quite a lot. If you mom has the cash to spend and doesnt mind losing like 10k over a few years then go for it.