Not a lot to do with the Nissan badge, in The U.S.A sales of The Zed series held up much better than The Z4 or The Audi TT, only Porsche did better.
Cars Sold in The U.S.A
Z4...........2004.......13,654, 2009..........3,523
350/370..2004........30,960, 2009.........13,118
Audi TT...2004........5,275, 2009............1,935
Porsche..2004.......31,473, 2009..........19,696 (Total sales of all Porkers)
Maybe our American cousins don't have the same badge snobbery as us though. I will attempt to dig out further sales figures when I get a spare few hours.
Pete