Sixt Car Rental Miami?

[gail-s]

Has anyone used Sixt Car Rental in Miami?  We're going to be staying at the Intercontinental the night before our trip, flying into MIA.  Husband wanted to stop into the Harley Dealer which is about 30 minutes north of where we're  staying.  I was considering renting a car from the airport, driving to the dealership, then cruising through Miami Beach before eventually making it to the hotel.  The Sixt company had a desk right at the Intercontinental, so that would be the easiest place to return the car to.  Any thoughts on this or experiences using them?  I can get a 3 series for $80/ day but sort of miffed that their Mustang is $400/day but Hertz offers the same thing for $100.