Looks like an official announcement about specific cars/tracks won't come until the day the time trial becomes available. Some speculation on this forum is that the 370z will be used on US tracks (Daytona, Laguna Seca, Indianapolis). There's also a GT-R academy version, so that might be utilized as well. Who knows...
I read the rules end-to-end, and it looks like round one is actually 3 time trial events that are open over an entire 5 week span. If that's true, I think the times will be very competitive in the last week, likely with hundredths of a second separating the top drivers.
Also - it looks like the national finals will be in Orlando. This might have been a mistake that an editor missed before publishing the rules. In several locations the rules just refer to the national competition in general terms, but in one instance it is referred to as the "Orlando Finals Bracket". This shouldn't be a shock - behind Vegas, Disney World is the 2nd biggest conference center location in the US.