black light racing. used to love watching it.
https://www.youtube.com/watch?v=1fq8OS00o9o
buggy VS stadium truck. i can't remember the class or race/event, but i remember a (full scale) short course race they run 2wd VS 4wd with the 2wd getting a handicap via starting X amount of time before the 4wd's start. make the quicker buggy's chase the trucks. this could also be done with 2wd and 4wd buggies.
some kind of vintage class could be fun. limit entry to cars over 20 years old. you could even take it one step further and designate it by time period. for example 1997 through 2003 vehicles only. or 80's night, could even encourage people to dress the part to earn bonus points that earn them better qualifying positions.
monster trucks. have some kind of 1/10 scale monster truck class.
some kind of endurance race with a 3 person team. an hour long main where all 3 team members have to drive. they'll have to make pit stops cause the battery won't last that long. allow tire changes and chassis repairs as well.
something as simple as a mini race could be fun. running 1/18 scale or whatever on a 1/10 track is actually amusing.
qualify running the track one direction and run the mains the opposite direction.