The Mears Fare Estimator said that the fare from MCO to Universal Studios (they didn't have a separate selection for Hard Rock Hotel on the on-line estimator) would be $29.75 so we thought we would save some money by taking a cab instead of a towncar service which quoted us $82 round trip with grocery stop.
Of course, once we got to the cab stand at MCO, we were informed that that cost would be $39 to HRH. The cab they put us had a terrible odor of cigarettes and the a/c barely worked.
I strongly suggest hiring a car service.