Well, I never mapped a car before ; )
Let´s start from the end.. pixelating: check projector resolution and pixel aspect (4:3 or 16:9); also, what is your composition size in pixels and what is your footage resolution? Yes, a bad encoding can also produce artifacts and pixelizing, but you would also notice that out of projection.
Alignment out of sync: that´s all about mapping. There´s no magic on it. No matter how precise is your setup you will allways have to move a couple of points to make your projection to fit properly.
Specificaly mapping a car, you must realize that a car is 'almost' an 'organic' object, I mean, they are smooth, full of curves and angles. The best (utopic) way to map a car is to create your video footage based on a precise 3D model of it. I mean you have the 3D model of the car, then you surface it, animating the effects the way you want, position your virtual camera at the same position (in the 3D space) as your real camera is positioned in real world, and render!!!
Last edited by pfelberg
on Sat Mar 23, 2013 13:50, edited 1 time in total.