I would say these cars are always going to be difficult to shift at best with anything like this kind of thing. The right car or an OK at the right price I think will always sell....and fairly quick whatever the time of year of the price is low enough. Like anything I guess....if the price is low enough it will always sell. I agree for the wrong time of year as a distressed sale be prepared to have your pants pulled down. That is the exact reason why I never allow myself to be in a position for a distressed sale. My pot is not overflowing by any means but there is always a bit there to allow me to reach a decent price when selling.
I would always prefer to buy a cheaper car and spend a bit of money know stuff has been done and done right. Rather than buy a medium or high priced car that shouldn't need much doing but then finding you still have to shell out for stuff. If I had a crystal ball I would be writing this now I don't think
You pays your money and take a chance....who knows what the future will hold. I had an R129 SL60 AMG for a few years that I sold to an enthusiast who wanted it at that time. The price was fair for both at the time but I could only sell at the price I did as I bought very cheap originally. Did some work myself over the years to get it to a better level as it would have been worth much less without.
I am not looking to buy and sell a 4200 in a hurry so it will hopefully be with me for many years. I don't mind investing a bit of time and money over the years.