Quite a few points to take note of...
Audi will be your best bet as they offer 4.8% APR on their PCP deals.
What is the car to be used for? Weekend toy, the daily runner or something inbetween? This will then allow you to set the lowest mileage term for your needs which will help on the 3yr residual value, the lower the mileage, the lower the payments. If it's a weekend car, you'll more than likely get away with 5000m per annum, if its a daily runner, you may want to up that to 10-15000m per annum.
Negotiate hard on your discount, you want to be financing the least amount possible, you should easily get 10%+ off a new order.
If you're watching the pennies, keep optional extras and thus depreciation as low as you can get it, adding the Ceramics (£9.4k) and B&O (£6.3k) you'll pretty much have to pay for these outright within your monthly payments which will send them rocketing over a 36 month term.
You are about 1 week too late, Audi last week revised their GFV's for the RS6 down by a considerable margin.
http://www.audi.co.uk/explore-models/fi ... &period=36
For example, 1 week ago...
Today...
Everything, mileage, deposit, term exactly the same. For the same car, look at the difference in the monthlies due to the change (£895.58 vs £735.66 -
Approx £160pm difference)
This is obviously on a base spec car, the more options you add, the more those amounts will increase. The GFV doesn't change much with options, so you have to pay for them pretty much outright during the term.
Reasons for the change? Perhaps the bigger discounts now being offered will have an effect on their 3yr valuations, or perhaps Audi will want you to have a good amount of equity in your car at the 3yr point to put down on your next Audi? The question is, how much is a C7 RS6 going to be worth in 3yrs time? With discount and base spec with no options, you can get the car down to £69k, if it's guaranteed to be worth £46k at 3yrs then that depreciation is very very good for this type of car (Retaining 67% at 3yrs guaranteed) With the recent change, that has now dropped down to £40k, so Audi are now only guaranteeing its worth at 58% at 3yrs) - Maths based on standard car and 10+% discount.