You'd guess as mentioned it's a dealer ploy to sell new cars. I'd push them on a price just for the sake of it and then see if they try and tie you down to a new purchase. Before you ascertain this though ask them for the price, that should make em go a bit dodgy because the higher price if one exists will be on the understanding you buy a new car off them, and they will be able to play with the headroom in the discount.
Just looked and after the recent price adjustments for the top models, via a broker you can get 28% off the top spec cross plus 2l auto 4wd. £18,068.
Would be tempting if you could get silly money off them for yours, say £13-14k.