I have a new MY06, bought it in May '07 and I stuck in 2 litres on 2000 miles as the dip stick was on the low level mark - I am sure it needs more as I am now on 2800 miles but I have not had the chance to check as whereI park the car is not level - I can tell you this - if it needs more I will be dropping the car off to the dealer for them to sort out and I wont be taking sh*t from them like the last time (paintwork).
Just print out the 51 page thread that beavis and posted and drop it into the Service Managers lap - that should focus his attention
I must confess if it were me (which it isn't) and I suspected I had this problem, I'd get onto an oil consumption test by the dealer and I damned well make sure it failed that test
I will be monitoring my oil level closely, though to be honest it does not seem to be consuming as much now as it did. Changed to Amsoil at the last service. But will be keeping an eye on the situation in America. But with the situation with the Autocar Zed and this 51 page thread on www.my350z.com there does appear to be something amiss.