why not have her paint a picture of YOUR car..with or without you in it??? Pick a great setting, take some photos, and have her use them. I had a similar situation a few years ago. Had a friend paint my 79 911. She took photos of my driveway (concrete paver stones) and used it for the foreground. Then took hundreds of pics of the car itself. Put the two together and it turned out great. Its hanging over the fireplace right now! Or do something with a nice juxtaposition.... your car against an old barn or brick building. Just some thoughts.
Bob