if you're talking about using like rustoleum primer temporarily, that would probably be fine as ling as it is allowed to cure indoors before it sits out in the weather.
if you want a rattle can paint to do the entire car, well, i wouldn't do it. if you think you need to, though, use the duplicolor touch up paints in the bigger cans and use their clear over it. we did the roof of a 944 porsche that my buddy got for his son's first car and he didn't want to spend a ton of money having the roof repainted for a 16 year old. the paint worked great and has been on the car for over 2 years without any problems. we allowed it to cure after the clear was applied for about a week then we sanded and buffed it out. like i said it still looks great after over 2 years, however the car only lasted for another 2 weeks after we painted the roof and his boy wrecked the car. it's been sitting in their backyard ever since then.