I independently confirmed this aswell. I recently bought the scrapyard property and capped out at 5000 from destroying police vehicles; in the SE train tunnel I called the police and continually lured them out only to destroy their vehicles in the tunnel (As bonus the train comes through and does additional damage to vehicles/cops/NOOSE). Once I'm out of ammo I jumped on a train heading north into yet another tunnel, erasing my 5-star wanted level.
TL;DR Do the weekly earnings roll over? I'm pretty sure after ~4 hours of the above I destroyed more than 33.3 vehicles....
Also how exactly is a week calculated in GTA V? Is there a way to speed it up? I think sleeping will fast forward you 8 hours but is there any other method?