This could have been real. I bet it would take a lot less time for Roger Federer to lob some forehands into a sunroof than it would be to make it look real on Final Cut Pro. As long as you're willing to risk some damage to a car, Federer should have had no problem lobbing a few balls in from a long distance.
But then you look to see who uploaded the video. It's from user mbusa, the YouTube account for Mercedes-Benz USA.
Racquet clap to @jon_wertheim