Pixar's Cars franchise isn't my favorite, but the kids love it, and it has grossed over a billion dollars at the box office. So, would it come as a surprise to hear that they might be developing a third movie? According to Michael Wallis, who has worked as an historical consultant and voice actor on the two previous movies, they are. While doing a radio interview with with WGBZ in Alton, IL he let the details slip, saying,
“Cars 3 we’re coming back to the road. And we’re coming back to 66 into 99. That’s the road that runs right through Central California."
Wallis is the author of a book called Route 66: The Mother Road, and also lent his voice to the Sheriff in the first two Cars movies. This is not an official confirmation of a third Cars film, but it looks like they're in the process of developing it.
Pixar has already carved out release dates for three films that haven't been announced--June 16, 2017, November 22, 2017, and June 15, 2018. I imagine Cars 3 could easily fill one of those spots.