Having read all (!) the comments on the subject I thought I would throw in my thoughts. I absolutely love a brand new car every three years or thereabouts. I know I'm paying through the nose for it even with a good discount, but who cares, I can afford it. In December I traded my nearly 3 year old, 5 door, Pret, DCC, manual, 20k, R bought for £28k and got £19.2k for it at an Audi dealership. I bought a brand new S3 specced up to £39.5k for £34k at my local Audi dealer after waving a Carwow quote at them which they matched. The reason I went for an S3 is because looking at VAG PCP finance figures, a similarly valued R at the time was worth £4.5k less than an S3. But of course these are all projections, so who knows what will happen. I must admit I haven't bonded with the S3 as much as I did with the R probably because it's DSG (as would a new R have been) but it is a bit plusher and with no squeaking door rubbers or rattles it does seem a little bit better put together. It also has a bit more kudos than a VW with the neighbours and friends.
On the other hand 18 months ago I bought a 6 month old ,ex demo, 1.4k miles, SLC 250d from a Merc dealer for £26k, list price with options £41k. That shows you all you need to know about depreciation, it's still dropping in price like a stone but I don't care as it's a keeper and it's great on a sunny day with the top down and for a diesel goes like a train, and gives me 61.4 mpg.