Just in reply to me1972.... I'm not on official business (doh!), otherwise it would be even cheaper (and no underage surcharge!)... the rate I'm using is a 'staff benefit' one... that is a very good one anyway - it seems to be one that Hertz offers as an additional benefit to IBM employees.
I'll make sure I bring a few business cards with me in case they ask any questions though, thanks for the tip. (I assume business cards are enough, I don't want to carry around my ID on holiday?)
lv