If you like to drive around, great. The gas is not free (unless work is paying for it), and just racking up miles to be spiteful is not how I would do things.

I once knew someone who tried to mess up rental cars as much as possible, without showing damage. So he'd pull the emergency brake while at highway speeds, go full speed over speed bumps and the like. Seemed pretty dumb to me, and could obviously endanger a future renter of the car.