You need to be quite a bit cheaper than a main dealer due to the risk to the buyer. I sold my gtd last year and had it up privately for a few weeks first but got no end of stupid offers. In the end was lucky that managed to flog it through the dealership I work for and for that reason quiet alot more. In my opinion if there is a main dealer car and yours side by side it needs to be at least £1500-£2000 cheaper due to risk presented by the no come back of a private sale.
I don't see why you think the "no come back" is a problem for a potential buyer, the car still has about 12 months manufacturers warranty left, and the price seems very reasonable to me.
It's not only that, there is a difference between what a car is "worth" and the dealers screen price.
The dealers screen price has to include dealership overheads, bills, rates, insurance, staff wages, VAT on the profit, the list goes on.
I reckon if you took the car to a dealer and offered it to them for cash, you ought to get around £17,000. With that in mind, I don't see that you can expect to get any more than £17,500 as a private sale. I'd advertise it for £18,000 with room to come down. Unless you're dripped up and in negative equity.
