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. And how!!! 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: At least for Pixar movies. This was more or less one of the criticisms of the first movie was that it's pretty much Strictly Formula and pretty much follows the basic plot of most Pixar movies to the tee. However, many consider it to be Troperiffic as well.
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.
Creator's Pet: Mater. Many older fans aren't fond of him, largely because he's voiced by Larry The Cable Guy. This hasn't stopped Pixar from featuring him in all the shorts and having him practically be the main character of the sequel.
Critical Dissonance: The sequel has been not very well received by critics, yet loved by its target audience.
Ensemble Dark Horse: Mater was one of the principle characters in Cars, yet was still one of the many characters in a more Ensemble Cast. However, he is the star of Mater's Tall Tales, and is the protagonist in Cars 2, with all the trailers and the whole story focusing more on him than Lightning.
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 Fan Dumb 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 the Pixar Hate Dumb 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).
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.
Needs More Love: The first film was generally well-liked when it came out, even if most aknowledged it was far from Pixar's best film. In the years following it's release, it has garnered a rather strong Hatedom, particularly when the sequel was released. As a result, people have become much quicker to regard the first film as bad by association. In it's defense, the first film is far from bad even if it's a weaker Pixar effort.
A deleted scene in the first movie shows a discarded scene which involved, while getting lost trying to find Mack, Lightening 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.
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.
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.