The best is often to go to an official dealer of the make, even if it's a little bit more expensive, it's more secure. Personaly, to make the maintenance of my car (320d Touring now), I prefer to go to a bmw dealer. It's maybe 20% more expensive than in a private garage, but it is more sure. For the other makes, it's always arround 20% (I had Alfa, Bmw and Peugeot mainly, the difference is arround this figure). Then, when you've a new car, under warranty, you must make the maintenance in a dealer of the make or of the group. Otherwise, the warranty is not any more available.