I'm a longtime Dollar customer and have been treated very well by them. No complaints here.
The price discrepancy here is enormous! Just for fun, I tried looking for a SUV at Denver for a random 10-day period in May, and found numbers similar to yours, except for Avis which was around $1600. Perhaps, though, a Dollar SUV is a "smaller" vehicle, like a Ford Escape, and a Hertz SUV is a bigger one, like an Explorer? That might explain the price discrepancy.
In other words, the numbers look legit. I'd take the Dollar price!
