Had a good chat with a Honda car dealer when I purchased my used car earlier this month, and he made a few interesting points.
The new car market isn't where they make money these days as they don't have many people purchasing new cars, it's all about selling Joe bloggs a used car and then getting them to service and ultimately part ex the car back with the same dealer, and then try and get them on finance for it all, and they also make a good amount on retro fitting options on a used car that someone is about to purchase.
He also said it's pretty much a myth they sell convertibles cheaper in Winter, they go off book price and thats that, should they have the car a set amount of time they would then re-price the car accordingly, be it winter or summer. Keeping a used car for a few months isn't a big problem for most dealers. Private sellers and indie dealers are a different matter.