Simple answer - dont buy new unless you want to lose a stack of cash in a few weeks. Examples:
I bought one last week privately, with less than 500 miles on the clock and 4 weeks old for £22k.
There was an ex demo car with 1000 miles on it which Renault in Bury St Edmunds had on at £22.5k last week - that was only 8 weeks old.
There were another 2 which were available last week privately, both only a few weeks old and both at £22k.
The other alternative is to buy an unregisteted "showroom" car. Theres a blue one at Renault Kidlington which I know they want to sell. You may get it for £25kish, but youll lose £3k on it as soon as you take it home.
As always, you pays your money...