Was over to Tokyo and then Kanagawa (actually Minamiashigara) for a long weekend. One place we visited was Saijoji. This would be an easy day trip from Tokyo, and something that someone going to Hakone should definitely tack on before or after. From Odawara, take the Daiyuzan line to its end, and then hike about 5-6km up to it. (FWIW--we were driving, and there's plenty of parking.) I'd suggest that JREF do an article on this--it's pretty important.
At present, my car is this type but an older one.