I never had much interest in attempting leaderboard records for the majority of the single player events, primarily because luck is a very heavy factor in terms of the AI's energy consumption and inconsistent behaviors, aside from obvious cheap tactics that can totally screw up a good time. Combine that with the fact that the infinite weapons glitch exists, and it makes it pretty pointless to try to get a legitimate time.
However, I have been planning on doing a single segment speedrun on Twisted Metal, on twisted difficulty, since it hasn't really been done before. It'll essentially be a run to complete the game from start to finish without restarting any events, and will include things like menu and load times. I've also been considering not using the garage for it since I find twisted difficulty too easy in the story mode due to the 2.5x health buffer.
I did a few practice streams of it at the beginning of the year, but I had no strategy going into it, so I've got to figure out a few things like the paths of the Juggs, and map out the altered pickup locations in the cage and boss events.
Also, I have, and am planning to continue improving my times in the two events that require pure skill, and can't really be exploited with the weapons glitch, being the Diablo and Diesel races (the Sunsrpings race is void due to the deathmatch, and the fact that you time depends on the AI finishing quickly to start the next sequence). I have a couple videos, which I assume to be the current world records due to the times ahead of them being unrealistic to achieve legitimately, but I'm hoping to upload footage of better times inthe near future seeing that I have a proper game capture device now.