A racing term used when a racer drivers on the low side of a turn and gets a big run on the car in front of them in a race.
Commonly used on the service, iRacing... an online simulator
When users get the this run it is common for them to yell over the microphone. "oh I've got marks run!!" or "MARKS RUN!!!"
Lance McGraw was racing the Chevy Impala Charlotte motor-speedway when he got marks run on the car in front of him coming off turn 2, he easily completed the pass.