This can work, and cost is sometimes comparable to towncar service, but it might be difficult to do it for much less. I got a rate of $42 including all taxes and fees for each of the two rentals (MCO to WDW on arrival and WDW to MCO on departure), using DC discount (which did apply, even for a one-day rental, although the free weekend day obviously did not). With Emerald Club, this was quite convenient, since we used the rental car to go to DTD and grocery shopping (we are DVC members and stay at the BoardWalk Villas). In our case the drop off and pick up of the rental car was very convenient, since the Dolphin has a National service desk and the time of day worked out well. Hours for that desk have changed during the last year, so it may not be as convenient now. Also, rental rates fluctuate so much it's hard to speculate about what one might find for particular days. Always worth a try.