Roadsters make Hertz look like a bargain on the Z4.
I ended up driving a Toyota Land Cruiser around the South Island of NZ for two weeks (check out
Overland 4wd if you're ever in the market, great company) and then had a Holden Calais from Avis for a couple days to make it up to Cape Tribulation from Cairns.
Avis ended up sticking me with an A$15/day under-25 fee; turns out our Avis corporate contract only waives the fee in the US, not abroad. Then again, I had reserved an economy-class car and they gave me the Calais, so I guess it wasn't so bad.