With most of the big US films and series we list I'd assume that the most prominently cars are either provided by manufacturers or from the various companies that rent out prop vehicles to productions. Also, in the biggest US movies most of the numberplates are fake so the real plates (which may have frames around them advertising Bloggs' Oldsmobile of Cabot Cove or whatever) will be removed.

That said we do get the odd one, to give a couple more examples:
http://www.imcdb.org/vehicle_399638-GMC-Yukon-XL-Denali-2010.html
http://www.imcdb.org/vehicle_808580-BMW-528i-F10-2014.html

It's a lot more common in the UK to see dealer stickers as there are fewer fake plates and legally since around 10 years ago the numberplate must have a supplier on it and even before then many dealers put their names at the bottom of the plate.

Something related to this that I've noticed is that a surprising number of Ford cars used in early 90s British TV stuff (which is what I mostly like to add) have dealer stickers for a garage called 'City Ford, Slough' which is frequently quite distant from the locations where the series in question is filmed. I'm guessing they either acted for Ford in providing cars for TV use or maybe sold cars to the larger rental fleets.
CF: http://www.imcdb.org/vehicle.php?id=654012