Tony,
You are assuming that only the retail price would be affected when in fact the trade price would alter downwards to reflect the retail price. What you must all bear in mind is that the dealers margins are not that large after preparation, warranty, valeting, discount and commission are taken into account, (average is approx £1000 across country) which may surprise many of you. The most desirable cars in the best colour and sat nav, low mileage, etc etc will always make more money in the trade and retail. Look at the differences in asking prices on the Lexus locator, and you can see the trend. If you intend to keep a car for a long period then big savings can be made on "undesirable" cars of all makes, as a 10 year old is valued far more on condition.