Carburetor County is a county in the Cars world. It consists of three places - Radiator Springs, Tailfin Pass and Ornament Valley. The name is frequently mentioned by Mater, as it is the county they are living in, and the county in which Radiator Springs was founded. The other cities in the county are unknown.
In Cars: The Video Game, players start in Radiator Springs. When they finish Sheriff's Chase in Chapter 3, they would then unlock Ornament Valley. In Chapter 4, they would unlock the 2 sections of Tailfin Pass pronouncing that they were districts. The first time you enter Tailfin Pass in Chapter 4, the district would be the Lower Ends, while the other part of the roads of Tailfin Pass would be the Highlands.
In Cars: Mater-National Championship, after you beat Stadium Race 1, you would unlock Ornament Valley, and then Tailfin Pass after you beat Stadium Race 2. But all 3 areas were smaller than in Cars: The Video Game due to technical issues.
In Cars Race-O-Rama, the areas no longer have loading screens besides the PS2 version. In other versions, the player could explore the Carburetor County map with no loading screens. They were the same sizes as in Cars: The Video Game, but new roads were cut in a few locations that are also accessible to the player.
In The World of Cars Online 2, Radiator Springs would be the first map that the player would unlock, then Ornament Valley, then Tailfin Pass, and so on. While in The World of Cars Online, the first map would be Snowhood Valley, then Radiator Springs, then Willy's Butte, then Fillmore's Fields, then Redhood Valley, before it got to Ornament Valley, Wheel Well, and Tailfin Pass.