I've only ever found one main dealer which has staff that are actually seem interested in / know about how cars work.. GTI world in Edinburgh, where I bought my last Golf.
They're not exactly local to me though, and after experiencing some problems with my R32 (suspected failing rear diff), I took the car to a local dealer since the car had a years warranty.
They sent the 'service manager' out to have a chat with me. After me explaining the symptoms, he said something along the lines of "the thing is, these R-line golfs don't really have 4 wheel drive, it's an electronic diff that simulates 4 wheel drive".
At that point I thanked him for his time and left