well if you look at the picture it must have been at night and he used a hose on the car/parking lot because the way the water is beaded on the hood/roof after you wash you car and it not running off from a downpour just sitting there beading??? and no constant rain on the right side of the car/windows etc... but held the hose just right to hit if front of the headlight to simulate rain.... 
plus no water streak on the windows from it "raining" ...
After looking at the photo again,
Tricky, tricky, tricky.
Anyway, that is still a good photo.
