Dollar and Thrifty appear to usually match rates at MCO, so if the Dollar rate hasn't changed, you should be able to get the same rate at Thrifty. Of course, if the Dollar and Thrifty rates have both gone up, then there's not much you can do.

Also, you can usually save $1-2 per day over the Expedia price by booking directly at dollar.com and/or thrifty.com (or directly at any agency's website).

How much is this "high" additional driver fee? It can't be much more than the $5 per day that I'm used to.