When Lightning has finished the road and decides to have a shopping spree before leaving.
Right before he leaves Radiator Springs, Sally thanks McQueen for everything he did. He responds, "It was just a road," and she answers back, "No, it was much more than that." It contains a double meaning. McQueen didn't just fix the road, he helped fix the whole town back up and gave everyone a newfound sense of pride for their town. But also, for many people—in both the movie AND real life—Route 66 was much more than just a road. For many, it was a way of life and a thing of wonder, something that ought to never be forgotten.
After helping the King, Lightning turns down a big-time offer from the King's sponsor. Then after a pause, he says "Actually, there is ONE thing you could do." Cut to Mater riding in a helicopter, having the time of his life, because he's always wanted a copter ride.
With Doc as McQueen's new crew chief, you see the rival pit crews look up at him in pure awe, and the camera crew have a mini freakout when they realize it's the Fabulous Hudson Hornet. Soon after the announcement is made, a few fans a heard realizing it and soon you see the crowd shift and realize the entire stadium is cheering for him. The industry may have moved on, but the fans never forgot him.
In Cars 2, Mater's falling out with his buddy Lightning may be a bit forced, but at least Mater takes the time, before heading out on the secret mission, to write him a farewell letter saying how he is sorry to be such a burden on this trip and feels it is best for him to leave early. Guido agrees with this Crowning Moment.
Near the end of the film, Lightning feels bad for the way he treated Mater. And wants to reconcile with him, even while he's too busy stopping a bomb.
Holley Shiftwell finally requiting Mater's feelings for her with a Meaningful Echo.
The Piston Cup being made into a memorial for Doc.