At Luigi's Casa Della Tires, Guido tries to remove a hubcap from a customer's tire and ends up flinging it out the window. It flies past Mater and Lightning McQueen, who are driving along Main Street. Mater immediately tells Lightning that it was a UFO and he knew because he'd seen one. Lightning says, "What?!", and Mater begins his story.
On a crystal clear night (except for several storm clouds building up behind him), Mater is driving towards a level crossing when the lights start flashing. Mater is puzzled because he can't see any trains coming, but when he looks to his left, he sees a ghostly, glowing, blue, buck-toothed UFO staring at him. He jumps back in fright and starts quivering, but settles down when the UFO smiles at him. Mater then introduces himself and the UFO introduces himself as Mator. Mater then takes him to his "liters": a pile of oil cans. Whilst drinking, Mater unintentionally teaches Mator to say "dad-gum", his signature phrase. Then, when Mator drinks a large can of oil in one sip and belches loudly. Mater later teaches him to tip tractors and drive backwards. Mator also teaches Mater how to fly, which startles Fillmore to the point of laying off the organic fuel he was having. As they start flying around Willy's Butte, spotlights surround them and Mator is captured. Mater follows them and realizes that his new friend has been captured by the military forces. He then sneaks onto base using his flying technique, quick movements, and a disguise to free Mator.
Lightning doesn't believe Mater, asking him, "Do you really expect me to believe that?" Mater replies, "Well, you should. You was there, too."
As the military forces chase Mater and Mator, Lightning joins them. Suddenly, a huge UFO mothership (presumably Mator's mother) arrives and takes the trio away, leaving the military to watch in amazement. She then drops off Mater and Lightning back home before leaving.
Back in Radiator Springs, Lightning still doesn't believe Mater, so Mater tries to prove that he can fly. As he tries, his engine makes a horrible spluttering noise and Lightning drives away, begging him to stop. He fails to see Mater actually flying past Fillmore and Sarge. Fillmore, dumbstruck, gasps, "Far out!".
In the final scene, Mater meets Mator up in space and they fly away together.
- Lightning McQueen
- Mia and Tia
- Corporal Kim
- Captain Munier
- Scientist Pitties
- Mator's Mother
- The title of the episode "UFM" is an obvious reference of the word "UFO", which means "Unindentified Flying Object".
- This is the only episode in the series in which Mater does not tell Lightning that he used to be something.
- Fillmore's dialogue is stock footage from the Cars movie. He is voiced by George Carlin, who died in June 2008.
- This marks the first time in Cars Toons that a car that is not part of the main cast from Cars is seen in Radiator Springs (Luigi and Guido's customer). It is also the first time that the Tractors appear in the Cars Toons shorts.
- Parking Area 51, the place where Mator is taken to, is a reference to Area 51.
- This was the first time in the Cars series where Mater was flying. The second time was in Cars 2, and the third time was in Air Mater.
- The basis of this episode is somewhat similar to the basis of the 1977 science-fiction film, Close Encounters of the Third Kind.