I don't know how tied you are to Hertz, but.......

I''ve been Emerald Club with National since I was 21-- there's like a $5 underage fee on top of the Emerald Club rates, but if you're looking for larger cars, that might end up a good deal for you. I got Emerald Club free because of my CO elite status-- and they keep renewing it for free, although I only use it maybe 3-4 times a year but I maintain elite.