i would use mousesavers site for tips,
http://www.mousesavers.com/dollar.html
i see they have changed the name to dollar express but i received a coupon for an upgrade,you show to them at the counter..
hints for Dollar at sanford..
first leave your luggage at the carousel spinning around you could beat the crowd and go to dollar register and get your keys by the time everyone has gotten their luggage and then they get to the counter,very crowded,if you can split up let someone stay and get the luggage,
second check you deal, print your exact quote and show it to them, sometimes they try to give me a different code but i know i have the better rate, just say no, plus no to ins.(if you have it under you home policy) plus no to them filling up the gas. YOU can fill up from disney and still be full when you arrival back to Sanford.
three try to get an upgrade for free, the first yr he said boy it looks like you need a minivan for $10/day extra i said ok, then the next year he said just take a minivan free of charge,very nice..