Grem first appeared on the oil deck and as one of the Lemons who had thought to have killed Finn McMissile. He was next seen in Japan when he and Acer attacked Rod Torque Redline in the bathroom.
Rod then managed to pass along information to Mater (who happened to be there) regarding the conspiracy plot. Afterward, Grem tested Rod on an Allinol with the electromagnetic pulse camera that would be used to blow out the race cars during the World Grand Prix as demonstrated by Professor Z - who proceeded to kill Rod after Grem and Acer managed to obtain the information onto Mater.
Grem was assigned to use the camera on the race cars during the World Grand Prix. He aimed the camera beam at a racer and with the result of the Allinol heating up, blew out their engine. Grem and Acer also caused a big crash in Italy. After Mater, Finn and Holley tried to stop the Lemons, they were all captured. Grem was then assigned to kill McQueen using the camera but since Sarge and Fillmore switched out the Allinol with Fillmore's organic biofuel mixture, the camera beam did not work so properly.
When Mater discovered the bomb strapped to his radiator and McQueen chased Mater down to see what the situation was, Grem and Acer pursue them throughout London until Holley Shiftwell intervened and threw Grem and Acer off the road and into the Ye Left Turn Inn restaurant where they got beat up by cars bigger and stronger than them. It is completely unknown what happened to Grem and Acer afterward, but it is likely that in case they were not beaten to death by the car clients (as they were just angry albeit most probably without murderous intentions), they were later taken in custody as the other Lemons.
Grem and Acer unloading cargo, as seen through Finn McMissile's camera.
Grem and Acer about to show Professor Z the crushed remains of Agent Leland Turbo.
Grem, Acer, and Professor Zundapp as Finn McMissile's shadow is cast over them.
Grem, Acer, and Professor Z seeing that Finn McMissile has been watching them.
Grem and Acer looking down to seeing McMissile had dove into the ocean.
"Get to the boats!"-Grem and Acer rushing to prevent McMissile from getting away.
Grem's evil laugh, thinking he and Acer have killed McMissile.
Grem at the World Grand Prix party in Japan with Acer, Zundapp, and a disguised Agent Rod Redline.
Grem and Acer finding Rod Redline in the men's bathroom.
Grem and Acer ready to attack Rod Redline in the bathroom.
Grem ramming into Redline, badly injuring him.
Grem about to charge at Redline
Grem fighting Redline.
Grem and Acer cornering a badly injured Redline.
Grem and Acer about to attack Redline one more time.
Grem and Acer being interrupted when Mater appears out of a bathroom stall.
Grem and Acer ordering Mater to leave; not knowing that Rod secretly put the device containing the information on the Lemons' mastermind onto Mater.
Grem and Acer demanding Mater to leave.
"I gotta admit. You've tricked us real good."-Grem to a captured Redline.
Grem getting angry as Redline taunts him and the Lemons.
"Smile for the camera."-Grem aiming the EMP emitter at Redline to torture him with it as he's being run on with Allinol.
"Could I start it now, Professor Z?"
"Roger that, Professor Z."-Grem after Zundapp figures out Mater has the device.
As the torturing of Redline continues, Grem receives orders from Zundapp.
Grem receiving orders from Zundapp to find and kill Mater.
Grem receiving orders from Zundapp to use the EMP during the first race of the World Grand Prix.
Grem aiming the EMP at a racecar.
After hitting a racecar with the camera, Grem is shocked to see Mater in the pits.
Grem telling Acer that Mater is in the pits.
Grem resuming his position as Acer goes to confront Mater.
Grem's laughing evilly after he injures another racer.
Grem and Acer finding Mater at the airport.
Grem's rocket blaster
Grem and Acer using the camera during the Porta Corsa race.
Grem and Acer greeting a captured Mater as they prepare to use the camera on Lightning McQueen.
Grem and Acer telling Mater their "backup plan" which is to have a bomb go off at McQueen's pit when he makes a pit stop.
Grem and Acer preparing to go after McQueen and Mater after they escaped from the racing course which the bomb did not go off, thanks to Mater's rockets.
Grem and Acer getting their guns out to attack Mater and McQueen.