Just when I was thinking about booking a car for my NZ trip (using the NZ Hertz site) I noticed this in the T&Cs of a domestic US reservation I just made.

sure gives one pause...

"This reservation is based on information you have provided Hertz, including information regarding your current geographic location.Hertz reserves the right to demand proof of what you have told us. In particular, if you have indicated that you are located outside your country of residence, you may, at the time of rental, be required to prove where you were when this reservation was made, through evidence such as an air or rail carrier ticket receipt, a hotel bill or a utility bill addressed to you at the location where you say you were. Failure to provide such substantiation may invalidate the rates you have been quoted, or invalidate the entire reservation. Providing false information to Hertz in connection with this reservation would also breach your rental agreement and could violate the law."