The 370Z has serious oversteer, and with the default being set at 7, I felt it would be comparable to the other cars if set to 2 instead of 0. 2 seems to work in a way that is comparable to the effects of turning off the traction control for the other cars. And yes, I have to agree with Nosoks - the :fucking tuned cars are like driving a row boat through a Kayak course.
As far as getting Motegi or not, I suspect we will get it since it has already been modeled for GT5 (and insures that PD/Sony will get more money from their "DL Content program"), albeit whether it has a weather feature or not. I also suspect that Motegi will come in more than one track configuration. We've seen Motegi East Course, but there is also Motegi Full Course, Motegi West, and the superspeedway. I believe that PD/Sony will release some or all of them in the future to keep game interest and boost overall sales.
Like with any of the tracks, PD has the ability to reconfigure them from the GT4 resolution levels to the GT5 resolution levels. The real surprises we got in this game was Spa and Monza and Madrid - they were all new tracks that never previously appeared in any of the previous GT's. The ability to re-model the tracks from GT4 to get them up to the GT5 levels of detail and resolution is there, but a cost effective analysis is what drives the ability to take the time to re-do them. In the case of Motegi, I believe that the excitement and attention given to the GT Academy drives the ability to put this "new" track into the mix.