In Cars 2, cars go to Europe and Japan which shows that its the same planet as all the other Pixar movies. It also shows that there are no humans throughout the world. The world at this time ends up with an energy crisis as oil is the only energy used for cars.
Allinol corporation was using green energy as a catalyst for a fuel war in order to turn cars away from alternative energy sources. That clean fuel could have been used to swiftly wipe out (decommission) many of the cars. Allinol was run by BnL which eventually polluted the whole earth due to its use of oil. The whole world becomes unfit to sustain life.

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Disney Pixar Theory
RandomI found something cool on the internet last week, and now I'm like obsessed with this. Ok so basicly there is this theory going around about how every single movie in Disney Pixar takes place in the same universe. If you like this and want more theo...