You are correct: most 1/24 scale car kits have the doors molded in the closed position. Probably because most cars & trucks are seen with the doors in the closed position when they are in use or sitting on a parking lot. Sometimes you just have to pick a model & open the doors yourself.
Now, I did a quick search through Cyberspace, and I did find that the Fujimi Lamborghini Veneno has opening doors:
Or at least the box shows it with the doors open. Actuall, several of the Aoshima & Fujimi Lamborghini models are shown with open doors. Same goes for the 1/24 Tamiya Mercedes-Benz SLR McLaren.
(This is actual photo of a completed model)
The only car I found in 1/25 scale was the AMT Piranha Spy Car:
I'm not exactly sure what Master Box was thinking. Good luck with your search. Try here: Hobbylinc