Hertz's rates do seem to have gone up, particularly on the Prestige fleet. I've been trying to sort out a rental for the in-laws between PHX and LAX, and for a convertible, Hertz is quoting me $1250 for 10 days if I book via Hertz in the UK, or $2200 if I book via Hertz in the US.

If I book via a consolidator in the UK, I can get the same car for £370 ($555) - though sadly with Dollar.

And this is booking 3 months out