On last week’s Tokyo Eye (NHK World, every Wednesday 9:30pm GMT) they featured some excellent alternative transport for getting around Tokyo, and in Akihabara you can rent street legal go karts to make your way around town. At the time of watching it was 2000¥ for an hour which they said was about enough time to drive to Ueno and back.
More details on their blog if you read Japanese http://ameblo.jp/akibacart/
Alternatively Kotaku have a post up here http://kotaku.com/rent-go-karts-in-tokyos-geekiest-neighborhood-476415858
Unfortunately NHK World doesn’t have catch up, but you can watch some shows online. If you’re interested in anything at all Japanese it’s worth taking a look at their schedule (and a lot of the shows are interesting even if you’re not specifically into The Japanese aspect)