Ownership doesn't mean anything about who makes their own cars. Mazda is mostly owned by Ford, but Mazda engineers still design the Mazda product. MB, not Chrysler, still makes MB.
Talking about rebadged vehicles: Audi is the worse when it comes to this. The A4 is simply a Passat with different sheet meatl and different badges. Plus, VAG has been underperforming for over a decade now. So even if Audi was an independent company, I wouldn't want to buy their stuff.