How does the economy of Radiator Springs from the Pixar movie Cars work?

In the movie Cars, the town of Radiator Springs has no tourists pass through it. This suggests that money is not flowing into the local economy meaning that whatever money in town merely circulates. How would this happen if some businesses offer necessities such as oil, gas, or tires; while others offer nonessentials such as paint jobs, army supplies, or lodging. Wouldn't all the money eventually gather and remain in the important businesses/services.