These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Base Breaker: Mater. While children seem to love this character, most other people despise him. There's pretty much a consensus that he ruined (or at least severely hurt) Cars 2.
There is also a subset that will Take a Third Option, finding him tolerable in the first movie, but obnoxious in the second.
Broken Base: Were both movies good or the weakest films that Pixar has produced thus far?
Cliché Storm: Cars is considered to be one of these. It's easy to imagine a little counter in the corner dinging whenever you see a Pixar cliché. Stranger in a community or group? Check. Brooding moment from a side character? Check. Wacky sidekick who forms a comedic duo with the main character? Check. Said group full of wacky members with their own quirks? Check. All of the development threatens to go downhill when something happens to separate or alienate the stranger? Check. They all decide they like this new stranger and want him back in the group? Check. The stranger decides that s/he really is a member of the group? Check.
One of the major complaints about the sequel is the fact that the Cliché Storm element is taken to nigh painful extremes. The clichés were even more evident in Cars 2 because they were using action-movie clichés too, more notable than simple Pixar clichés.
Critical Dissonance: The sequel has been not very well received by critics, yet loved by its target audience.
The first film also received the weakest reviews of any Pixar film at the time, yet audience response was much more positive.
Family-Unfriendly Aesop: To more conservative viewers, the sequel's "once big oil, always big oil" message might come across as one.
Something to dislike on both sides of the spectrum as the Aesop can also be viewed as alternative fuel is an evil scam.
In addition, as far as the friendship between Lightning and Mater goes, Cars 2 can come off as, "Be yourself, even if your true self is a jerk who constantly embarrasses everyone around you and creates big setbacks for your friends."
Harsher in Hindsight: Connect Doc's "they quit on me" speech with the fact that this was one of Paul Newman's last major roles.
Narrowly averted in Cars 2: The weakness/trigger of the new fuel was supposed to be radiation but after the nuclear power plant meltdown in Japan they changed it to radio waves (as of John Lasseter's "Day in the Life" documentary).
Back when the first movie was released, MAD did a spoof that mentioned (among other things) that they cut an appearance by the "Popemobile" at the last second. Well, guess what actually appears in the sequel...
A year after Cars 2, James Bond would have to deal with his age in a similar manner as Finn McMissile, right down to the Aston Martin.
Ho Yay: In the sequel, Mater puts together quite a day out for his best friend when he comes home, and even tries to infiltrate Lightning's date with Sally. They have a secret handshake that a bystander notices gets longer every time they do it. If that's not bad enough, at one point Lightning chases after Mater repeatedly yelling "You're the bomb." Yeah...
Fillmore and Sarge have lots of this. Despite their clashingpersonalities, the two are almost inseparable. The two are almost always next to each other, Sarge is even shown sleeping next to Fillmore in "Unidentified Flying Mater". Twice. Some of the toy packaging go as far as describing the duo as being "Unable to live without one another."
Internet Backdraft: Lots regarding the sequel, going from diehards saying that the film only seems bad in comparison to the rest of Pixar's work (and calling any and all critics of the movie "haters" who are gleeful that Pixar has finally produced a genuinely bad film) to persons who actually are gleeful that Pixar has finally produced a genuinely bad film (and wasted no time in rubbing it in the noses of said diehards).
Quite a few Pixar fan's reaction to the dual announcement of The Incredibles 2 and Cars 3 was "YES! Incredibles 2! But WHY THE HELL are they making another Cars movie?!"
Jerkass Woobie: The Lemons themselves from the sequel. They might have done many wrong things, but it is hard not to feel sorry for them when they were made outcasts by the others.
Moral Event Horizon: Chick Hicks, the film's antagonist, was already bad due to his dirty racing tactics, but at the end when he purposely runs The King off the road — causing his crippling crash — and has no remorse for it, he unsurprisingly loses all his fans.
Nightmare Fuel: A deleted scene in the first movie shows a discarded scene which involved, while getting lost trying to find Mack, Lightning Mcqueen wandering through a car graveyard full of rusty and destroyed cars. The scene seems reminiscent of Snow White getting lost running from the wicked Queen and it's not hard to figure out why the scene wasn't in the final product.
Also the fact that they based King's crash off an actual crash Richard Petty was in at the Daytona 500 might count. Sure it's bad enough the cars are alive in this movie, but the fact that an actual person had to go through that... sure, he made it out okay, but still...!
Some of the Family-Unfriendly Death in the second movie. Special mention must go to the death of Rod "Torque" Redline, who gets tortured for information by the villains, and then blown up. While his actual death is partially obscured as a reflection on a screen that's showing a picture of Mater, we get to see the explosion and the flames rising from his body. Not helped by the fact that it underscores an aversion of Never Say "Die".
Tear Jerker: The 'Our Town' scene, especially when Luigi pushes up the sign saying, "We're still open!"
Tough Act to Follow: Even if the second movie was more positively received, it still would have been considered very underwhelming compared to Up and especially Toy Story 3 before it.
The first film was also victim of this; coming right after The Incredibles.
Uncanny Valley: In Paris, Mater comes across a car that has its eyes in its headlights instead of on the windshield (a possible Take That toward previous depictions of anthropomorphized cars). Mater (and the audience) are suitably horrified.
If you take the ableism out of it, it's a classic Class War. They outright say to your face that the villains are all lower-class cars (direct quote: "history's biggest loser cars") and The Man Behind the Man is an oil tycoon. If the heroes weren't unbiased law enforcement agents who just want to save lives, things would get really uncomfortable really fast.
Viewer Gender Confusion: Two race cars, one pink, one blue. One's a boy, and the others a girl. And it's not the ones you're probably thinking of. Family Guy did do this gag years before, but it was a parody of the Chevron claymation car commercials that aired in the late 1990s.
The Woobie: If you notice very hard in the "Our Town" sequence, Mater had a coat of sky blue in the flashback. When customers stopped coming to Radiator Springs and business closed and all the cars are looking at the empty road, the first car to leave in disbelief is Mater. Plus, he is the one who has physically changed the most- not a hint of paint left on him. And in the present, he's probably the most crazy of the bunch. Evidently, he took the by-pass the hardest.