Level runs should be played in time trial. The AI might behave differently in career, and the lap count may not always match with the time trials as well.
Actually, for IL runs we use the Single Race/Quick Race option with specific race settings (that can be seen in the IL rules). Time Trials don't have any nitrous and also only have a single lap, and while they indeed are way more consistent because there is no AI and You can't clean the track up beforehand, Lap Times with no nitrous is a very unpopular category in the community, so it was decided to make IL runs be done in Single Race mode like we do in FO2, while also making use of FO:UC's Race Settings option. I do wish that each track IL would also have Time Trial category for those who prefer them, but that may clutter the visuals of the runs' page I'm afraid..
But other than that - Kaopoke is right. We don't use career events because AI difficulty and laps vary between cups, and the career mode lets You install all but weight upgrades and get a slightly faster car that way. So all Individual Level runs should be done in the Single Race mode
Time Trials have their own category listed in Full Game Runs in Misc caterogies - it consists of finishing all time trials as soon as possible in any order You like =)
