Radiator Springs is a composite of multiple real places and landmarks on US Route 66.
Its highway map location most closely resembles Peach Springs, Arizona, a once-busy stop along the 2488 miles of highway leading westward from Chicago and Saint Louis through Kansas, Oklahoma, Texas, New Mexico and Arizona to Santa Monica, California.
Peach Springs is the administrative base of the Hualapai native first nation. In Route 66's heyday, it was a starting point for Route 66 travellers to take side trips north to Grand Canyon National Park or Monument Valley - diversions which would add hundreds of miles to a real Route 66 roadtrip but which look somehow compressed in distance in the film.
When Interstate 40 bypassed Route 66 from Oklahoma City to Barstow, California it took a shorter, more direct route from Seligman to Kingman in Arizona by passing further south, missing tiny Peach Springs by twenty-five miles. Most towns along this section (Hackberry, Valentine, Truxton) simply died overnight, but the Hualapai nation kept Peach Springs marginally alive. Nearby Williams (Arizona) was the last community bypassed (in 1984) and Seligman to Kingman was the first section designated as "Historic 66" (in 1987) due to the efforts of Angel Delgadillo of Seligman and his Arizona Route 66 Association.
The cartoon depiction of Radiator Springs and Carburetor County is based on a composite of multiple landmarks in multiple states, from Baxter Springs, Cherokee County, Kansas to Peach Springs, Arizona and a bit beyond. A group of fifteen Pixar designers packed into multiple longhorn stretch Cadillac motorcars and took to the road to visit NASCAR racetracks, Detroit automakers and more than 1200 miles of US Route 66 from the Kansas-Missouri border westward through Arizona.
A list of places visited could be reconstructed from the film's credits and trailers (which list key people they talked to along the way), from route66news.com descriptions  and from local newspaper articles about individual towns through which the Pixar crews toured.
As the animated Radiator Springs compresses 1200 miles and five states of Route 66 into a few blocks of road, this Route 66 road trip is presented as itinerary (effectively, a single east-to-west composite patched from multiple trips made as research to create the film) instead of as a single geographic village.
A journey of a few thousand miles begins with a well-maintained motorcar in top condition. As this trip crosses large expanses of New Mexico, Arizona and California desert, be sure to carry enough fuel, bring extra water and some means of calling for roadside assistance in the event of a break down.
Bring a copy of the main Route 66 itinerary or references such as the "Here it is!" eight-state map set, as this itinerary is specific to people and locations referenced in the film and does not fully cover the entire "Mother Road" of 'The Grapes of Wrath' fame. Grab a full tank of petrol and head onto the open road... and get your kicks on Route 66.
By car. From Detroit.
It's not what it used to be, but Detroit is still considered the birthplace of the US automotive industry and a film like "Cars" wouldn't be made without a visit to the home of Ford and General Motors. While the public doesn't have the same access to Detroit's automakers as the Pixar crew, the Henry Ford Museum and Greenfield Village in Dearborn is worth a tour; there's also an Automotive Hall of Fame. In Auburn Hills, the Walter P. Chrysler Museum is available for group and meeting rental but otherwise not currently (as of 2013) open to the public.
To get there from Detroit, one possible route is Interstate-75 south to Knoxville, then Interstate-40 east to Interstate-81. Bristol is about 110 miles (175km) northeast of Knoxville.
Got a flat? Bring it in. Don't tear yourself up out there, kid.
Watch for speed traps; Route 66 goes through every tiny town and odds are there'll be a sheriff at the town line just waiting to chase speeding motorists through the village.
Be sure you have enough fuel. You don't want to be in the middle of the Arizona desert when you find you've run out as someone has siphoned all of your petrol while you were sleeping.