There's not as much of a car scene as there was 15-20 years ago. People still gather at places like daikoku futo in the evening but it's not every evening like it used to be and often they're asked to move along fairly quickly now. if you gave some hint of when you'd be visiting and what sorts of things you're interested in I could probably help but I am a bit out of it these days. I've done lots of events like the auto salons, time attack up at tsukuba, F1, nismo festival, D1, yoho car show etc to workshop visits/tours to the more underground stuff like highway racing or late night drifting in Hakone before the police cracked down heavily on that kind of thing. There's still lots to do but a lot of it is a bit out of Tokyo so some hint of interests, time of travel etc would help a lot in giving suggestions.