VFD won't be projecting anything; your windshield simply acts as a mirror. Now, aditional problem is that you will probalby get reflection from several wintdshield's layers...

Try simple test with bright drawing on white piece of paper (or perhaps better, little pieces of tinfoil or similar bright bits on something dark) on sunny day with the car turned into the sun. Place it under the windshield and more around to see posibilities for placement and resulting image quality.

Hm, small display like this would perhaps benefit from a Fresnel lens...