When I was looking 18 months ago to replace my Scirocco, I tried a few different dealerships and marques, and here were my findings.
Audi
Looked at A3 Sportback S-Line - Totally apathy from the Audi dealers, completely ignored me on 3 separate visits to 3 dealers. When I did get to speak to a sales person, it seems I knew more about the car than he did (wouldn't have been hard really), and when he asked what I was currently driving, said "oh, a VW, you know most people start with a VW and then aspire to a Audi you know, after all Audi is all about quality, and VW is sort of....entry level". When I explained that 80% of the engine, electrical and running gear parts were sourced from Wolfsburg, he was in total denial and said all parts on an Audi were 100% designed for an Audi and not shared with VW, Skoda or Seat - which he all rated as entry level - yeah right - dream on my friend.
Offered the worst trade in price and the smallest discount off list. If I never set foot inside a UK Audi dealership in my life it will be too soon. Shame, as I really liked the A3.
Mercedes Benz
Looked at the then new A class. TBH, the dealer was pretty good and very knowledgeable. Came over straight away and offered me a test drive within 10 minutes. Average trade in price, and not enough discount but much better than Audi, and to be honest the whole experience was a lesson to Audi in customer service. Unfortunately I just didn't like the A class (as much as I wanted to), and the playstation add on screen on the dash, and the clunky C Pillars and poor rear visibility just didn't do it for me.
BMW
Went in to look at the 3 series and 1 series Coupe (now the 2 series). Pretty good experience overall, quite knowledgeable about their products, and plenty of choices on display and in the forecourt (one of the larger UK BMW dealers). Quite liked the 1 series but knew that a brand new 1 series would be coming along in 2015 (which it has), and the 3 series was also due a major refresh. Trouble with both was at first compared to the opposition, they looked quite good value. However, once you start adding the toys that come as standard on other models, the prices start to climb worryingly.
Offered equal best trade in price (with VW), and a substantial discount off list, but still (for my spec) just too expensive. Once thing though, they said they could get a factory build with what ever options I wanted in 6-8 weeks from order. I think now the line has been refreshed, BMW might be a serious contender for me next time (sorry guys).
VW
Bit unfair to compare this one as I know the dealership well (having purchased 6 VW's from them before). TBH, it was a bit of a standing joke with the salesman that I knew more than him, so he never tried to "sell" me the car. Good trade in price, and even though the GTD had just been launched in the UK (March 2013), still secured a decent discount, and also got a fixed trade in price for the Scirocco (which I purchased from them).
That was the good part, now the bad, such was VW UK's incompetence, that upon selecting my options for the GTD and having it all entered nicely in the computer and accepted, I was contacted 5 weeks later to say there had been a screw up on the configurations and some options were not available on the GTD and had to be removed, and the car had then gone in again as a new build. At this point, both I and the dealer had no real idea as to the price of the car, as VW UK, were still finalising prices and options ! In comparison to BMW's promise of 6-8 weeks, I was quoted initially 15-16 weeks for the GTD which turned into 23 weeks - for a bloody Golf ! VW customer services (or rather non customer services) got involved, but it still didn't change the fact that that despite ordering 1st week March, it was delivered last week in September.
As I seen recent posts (from MH amongst others) that seems to indicate VW UK are still up to their old tricks with monstrous delivery times to the UK, I seriously doubt if my next car is a new factory build it will be a VW. As I said most likely a BMW. VW, great cars, let down by abysmal UK agent and absurd delivery times (especially considering that the UK is one of VW's biggest European markets).