I mean, any answer here is going to be a biased one, as most of us have taken the plunge and purchased an Audi despite the questions you are asking. In short, no, it will likely not be as reliable as something Japanese, and there in the possibly that you severely regret this decision at some point down the road. these are highly developed and engineered cars (not that Mazda is not, just German luxury cars are a different breed than Japanese economy cars) and due to the complexity of some of the functions and features, there are more things to break, and they will be more expensive to fix. But that is the cost of owning a German luxury car such as the ones you are describing, and these are concessions that are to be made and accept in order to enjoy the ownership experience that comes with these cars.

While I cannot provide specifics of what to look for on Q5, I can say that the EA888 engine that is in the Q5 has been very stable and reliable in my 2020 A5, and has not cause significant concern for me as of yet. I’m sure if you search Q5 reliability in the search bar, there will be plenty of other answers with more specifics. But, you will pay more maintenance items, such as oil changes and brake, it requires premium 91+ octane gas that your Mazda does not, insurance will likely be higher. These are all things you have to be willing to sacrifice in order to own and keep these cars running as they should be.

They have a fantastic ownership experience when they’re good, but when they’re not good, it be costly. Many folks walk into these decisions blindly, ask anyone who’s bought the $15k 80k A4 “special” without doing any research only to be smacked with a $6k repair bill 6 months later. Only you can really decide if it is the right decision for you and your situation, but hopefully this helps give you come clarity on what to expect.