The idea for Pixar’s franchise Cars makes total sense now, but when the concept was first presented to the animators they weren’t sure what to make of the whole talking car thing.
The first problem- how does a car pick stuff up when their only appendage is an antenna?
This amusing animated short reveals how animator Rob Gibbs and the rest of the Pixar creative crew developed an anthropomorphic car character into the McQueen we know and love today.
-Via 22Words
There's a scene in a famous fan film that addresses this issue:
https://www.youtube.com/watch?v=_U0QDt8wiCs#t=03m30s