I used to be a "wrangler" for TV and motion pictures. Supplied a lot of contact's cars and some of my own. Movies, television shows, commercials, music videos.
And, as stated here earlier, it is quite literally hours and hours of extreme boredom, standing around....waiting for the 32 takes of the same car rolling into the same driveway, for 5 seconds of on film action....only to find when the perfect shot is finally captured in take 32 at midnight, some diligent PA views the rushes and notices what looks suspiciously like a booger peeking out of the nostril of the actor. "Wrap it up til 6am and we'll re-shoot it then".....ugh!
The first thing to understand is, while movie people are omnipotent, they are not car people. With few exceptions, they are extremely hard on cars and have little regard for the owner's feelings or post-production whining about damages.
Every prop used is just that, a prop. And nobody (besides the prop master, and he only cares about his own props) cares about any prop, anywhere, any time, ever. I pretty much handcuffed myself to any car I supplied for the entire time of the shoot to keep the cars safe from the scores of PA's and others "below the line" who just assumed they could use treat the cars as a hay bale (which is/was common terminology for cars). A minor but infinitely annoying peeve of mine, was the use of "dullers" on paint and chrome.This is a very common practice to avoid glare and/or reflections and the medium generally used is simple hair spray. Again, ugh!
I was never at a loss to find people willing to offer their cars at absolutely no cost to the industry, just to be able to say "My car was in a movie!" But, honestly, nobody is making any more car movies like Bullitt, Gone In 60 Seconds, Smokey and the Bandit, Christine or even The Love Bug.
If you decide to offer your car, my strong advice is to prepare for at least 4 times the amount of time you are told at first. Bring a good book. And never let your car out of your sight.