Don't sell up yet.
House prices will continue to slide. If you buy now, your house will continue to depreciate meaning in 12 months time you could possible be in negative equity.
With regard to your car, you have done some pretty permanent mods like the bumper, spoiler and roof. These would look odd imo on their own....
I agree that you may make a bit more money separating the mods but you may be left with an unsellable car...........