So apparently, Cars’ original “working title” was Route 66, but was changed to prevent people thinking it was related to “other things”. 
“In 2001, the movie’s working title was Route 66 (after U.S. Route 66), but in 2002, the title was changed to prevent people from thinking it was related to the 1960s television series with the same name”
If it had been called Route 66, would the series have been as popular?. And the title is based on a road, would the film have been based on the road more?. Cars originally started life in 1998, as The Yellow Car, which looks like Luigi. 
The original script was called The Yellow Car, about an electric car living in a gas-guzzling world. Some of the original drawings and characters were produced in 1998. 
It was meant to be released during 1999, but was scrapped in favour for Toy Story 2, according to Wikipedia.
Original drawings can be found here: huffingtonpost.com/jim-hill/ … 90538.html