He goes by T-man.  He built a tumble go-kart, and is selling the plans on eBay.  We assume it doesn’t come with a utility belt, cape, or ambiguously gay sidekick.  But it does, apparently, work.  Watch the video below and check out these screen caps.

But, as admitted by the inventor, it doesn’t go in reverse.  But hey, Batman never backs away from a fight anyway.