Google to the rescue!
Taptalk.
I took a quick look at the requirements. The forum here is custom code and the work involved with integrating with the Taptalk system is more than we want to take on. This isn't a very high traffic forum, and it's almost completely devoted to site bugs and feature requests.
If we get to a point where there's a lot more activity on the fuel talk side, or if we end up doing more with discussion forums we can revisit. But for the now the work involved wouldn't be worth the potential payoff. We have a long list of things we want to add to the site as it is and we'd rather put our time into developing the core Fuelly features.