Here's why:
* Appearance: Mater has a worn-down, rusty exterior with faded paint, suggesting he's seen a lot of use and time.
* Personality: He's a bit slow-witted and naive, but also wise and experienced in his own way, suggesting he's lived through a lot of history.
* Story: In the first Cars movie, he's already established as a respected member of the Radiator Springs community, indicating he's been around for a while.
While we don't have an official age for Mater, his character and appearance suggest he's a seasoned car with a long history behind him.