Like LK says there are insurance ramifications of letting employees drive company vehicles "off the clock".
You can also run afoul of the IRS. If they are using a company vehicle to "commute" that may be "compensation" and you might have to pay tax it (is it really "business use"?).
IBM ran into that problem when started buying guys a van and we let guys take their van home. They got around it somehow by saying it was a security issue (having a van with $100,000 worth of parts parked outside the shop).
They ended up making the guy's "point of reporting" his house so he got paid to drive back and forth from work.
Then the question became "how many stops can you make on your way home from work".
It was real can of worms.
