Although GTechniq C2v3 is a very very good product, personally I think (having extensively used them both) that Sonax Brilliant Shine Detailer tops it. Here is is beading on the roof of my winter car (54' plate Ford Fiesta that I'm borrowing until the GTI comes!)
Rather than leaving a really slick finish, it leaves a (for want of a better word) 'grabby' feel to the paint, but the water behaviour is amazing! Whats more, you can use it on paint, plastic trim, glass, pretty much anything.
The dealer (as above) will just wash and dry it, dress the tyres, and hoover the car unless you've specified LifeShine. If you have specified LifeShine (I recommend you don't!) then they will slap the treatment on without properly degreasing/claying/alcohol wiping the paint and it probably won't bond properly meaning you won't get the best from it. (Not the valeters fault at all... To properly apply would take at least 4-5 hours per car and they simply don't have the time for that).
My advice, is to get the car home yourself, properly wash it (2 Bucket Method), dry it (using a plush drying towel), clay it (using a fine clay bar and lubrication solution), hand polish using an AIO (all in one) polish like Auto Finesse Tripple, then apply the Sonax BSD. Then, for maintenance, top the BSD up after every other wash (it's so easy, just like using a quick detailer - < 10 mins) and you'll be protected for many months.
Sorry for the long post, just couldn't answer with a 2 liner! If you want any advice, PM me, or ask in the detailing section on here. Waxamomo (Forum sponsor) have most of the above products (they don't sell Sonax though) and offer a great service if you need anything.
Hope this helps!
Jon
