Decided to give this topic its own thread as it's kind of taken on a life of its own over on the Carnival.
It would appear that there is still an appetite for a kart racer in the ZDoom engine, and I for one would be only too willing to contribute to its creation. This thread is purely for the exchange of ideas at this stage. If enough people are interested and we end up with something concrete, who knows? Maybe it could end up as a proper community project.
If this project is to happen for real, here's how I see it panning out.
1. We need coders. Experienced ACS people. The mod will need to handle such things as kart physics, laps, lap times, player positions/rankings and appropriate respawn points for players who wipe out. Once the actual game mechanics are in place, the rest should be relatively easy.
2. Sprites and DECORATE. If we keep with the SNES SMK style already demonstrated on the Carnival, spriting different characters shouldn't be too difficult, other than the need for the full 16 rotations. Weapons and item boxes could be handled in DECORATE relatively easily using random spawners or pickup states, unless we go for the fruit machine style of weapon selection, in which case ACS would need to be employed. I already have the item box sprites done
3. Maps. The circuits really don't need to be that large or complex, although the sky's the limit here. It's more down to what themes to use in this regard, and I would be inclined to base the maps off areas from the IWADS themselves. For example, driving through a techbase and emerging into a huge atrium where the road gets rather twisty, with a drop into green ooze on either side. Sound familiar?
That's pretty much all I have for the moment as it's quite late here, but all input is welcome. For the record, I couls contribute sprites, maps and some DECORATE, but I would need a lot of help with the scripting.
My coment started a revolution! 
