I've never used it in cars only buildings but I do know polyurethane is the best stuff in the world for sound & thermal insulation. It also adds to rigidity. Ideally you'd go to a foamer that does houses and he may have a few squirts left at the end of the day but that would block up the window channels. The stuff in cans is decent (and much cheaper than the stuff you mention) just don't get the super expanding kind because it's difficult to control.
I took off my panel to try to fix my friggen window, the decided to spray a bit of Dupli-color Undercoat and Sound Eliminator (perhaps 1 sq ft total) onto the inside of the door panel. It helped! I'll be doing the pass door, and back floor
Next time I'll make sure to air out the car according to instructions!