Depends who's car it is and the situation. I usually either blank'em out (like on this local murder scene the other week - wasn't sure people would appreciate their cars being seen at a crime scene)
or use show plates
If you use show plates, remember to take'em off again before you return the car - I always forget, resulting in a police car giving chase the other night when I passed him near the dealership in a black Vauxhall with just "Astra" as plate - that was amusing...
Yes, officer - it's 2am
No, I didn't steal it - It's for photos - honest!
:lol: