Doc Hudson died off-screen between the events of Cars and Cars 2 , and Cars 3 treats him as already gone through flashbacks and memory. The franchise never gives a detailed on-screen cause, but fan and reference discussions generally describe it as old age or a serious engine failure rather than a crash.

What the story suggests

In-universe, Doc is understood to have passed away sometime after the first film, before the later sequels take place. The most common explanation is that his car body or engine developed a major failure that couldn’t be repaired, which fits the way the films treat aging vehicles.

Why fans talk about it

A lot of discussion comes from the fact that Paul Newman, who voiced Doc, died in real life, and Pixar then handled the character respectfully by using flashbacks instead of recasting him heavily. That’s why people often ask “what happened to Doc in Cars,” even though the films never spell out a single exact cause.

Quick answer

If you want the shortest version: Doc Hudson is dead by the time of the later Cars movies, and the implied reason is natural decline or engine failure, not a dramatic accident.