I work at a competitor to The Mill so I have a little insight into this process. Ad agencies have grown accustomed to spending an enormous amount of money on VF

I work at a competitor to The Mill so I have a little insight into this process. Ad agencies have grown accustomed to spending an enormous amount of money on VFX to make the cars in their spots look as perfect and attractive as possible (same with soda, people's faces, etc). They call this "beauty" work. For high end commercials this single line item can be over $30k (though I'm pretty sure The Mill charges more than I do). Most of the car commercials I do end up with full CG cars regardless of what they shoot because 1 they want the cars to look perfect, 2 they want to enhance the cars attractive qualities beyond all reality, 3 they want to be able to control every pixel, 4 they want to change elements of the car for different markets. That last one is probably a big reason The Mill would invest this kind of R&D in the project. Doctorpangloss's point about product placement is no small thing either. As foreign markets become a bigger part of box office take being able to sell 5 different product placement deals in the same 20 shots is a big win.