I wasn't initially a fan of the original "Cars" movie: I thought it was overly sentimental and not as funny as Pixar's best work. But in the end I became a fan: they make a virtue of the sentimentality, and I can enjoy that occasionally. But "Cars 2" I never got through: it's generally regarded as Pixar's worst movie, and after 20 minutes I had to stop watching. "Cars 3" holds onto the sentimentality (in a big way), and reminds me more of the remarkably pedestrian and weak "Planes" than the original "Cars."
Lightning McQueen (Owen Wilson), after seven years of Piston Cup wins, is finding himself being out-raced by new rookies with the very latest technology. To overcome this, he finds a trainer (Cristela Alonzo), a new training facility, and a new training philosophy. But they keep the old friends: Mater (Larry the Cable Guy), Sally (Bonnie Hunt), and several of the others return from the previous movies - although a big point is made of the death of Doc Hudson (Paul Newman - whose voice is used a great deal despite his being dead).
The critics thought fairly well of this one, with the "Critical Consensus" on Rotten Tomatoes being "Cars 3 has an unexpectedly poignant story to go with its dazzling animation, suggesting Pixar's most middle-of-the-road franchise may have a surprising amount of tread left." It's a fairly sweet story aimed at kids ... but Pixar's best (and these days other studios are managing it too) also nail adults right where they live, and this one fails completely at that. I'm not a fan.