Yes, we did. I tried to call up and get a rate for the 4 days before the cruise and the 4 days after the cruise and it was not cheaper than renting it for the full 12 days, even with the $40 fee to park the car in the
DCL lot.
I also used a Costco discount AND Costco had a tiny coupon inside their magazine for a Free Tank O' Gas! (WooHoo!)
Check your options and see which one comes out cheaper.