Do rough idle repair problems track solo operators as a share of all auto repair businesses across states?

Across U.S. states, NHTSA owner complaints about rough idle repair run higher where solo operators as a share of all auto repair businesses is higher, after adjusting for the makes sold in each state. This is an association across states, not proof that solo operators as a share of all auto repair businesses causes this repair.

How to read it: Each dot is a state. Further right means more solo operators as a share of all auto repair businesses; higher up means more complaints for this repair than expected (1.0 is average). If the dots climb to the right, reports of this repair rise with solo operators as a share of all auto repair businesses.

What it shows: States with more solo operators as a share of all auto repair businesses tend to sit higher on the chart across 28 states: a pattern in the data, not proof of cause.

• The 9 states with the most solo operators as a share of all auto repair businesses (Georgia, Florida, Texas, Arkansas, Tennessee, Alabama, Kentucky, South Carolina, Oklahoma): reports of this repair run 12% above what the makes sold there would predict, and 8 of 9 are above expected. The 9 with the least (Massachusetts, Washington, Connecticut, New York, New Jersey, Oregon, Wisconsin, Michigan, Illinois): 2% below, and 5 of 9 are above expected.
• Exceptions: Texas is among the highest in solo operators as a share of all auto repair businesses but reports below expected; Oregon (43% above expected) is among the lowest but above expected.
• Split the states into thirds: the third with the least solo operators as a share of all auto repair businesses runs 2% below what the makes sold there would predict, the middle third 8% above, and the third with the most 12% above. It steps up steadily.
• For solo operators as a share of all auto repair businesses, after allowing for the 1562 comparisons we ran, luck alone would produce a pattern this strong about 1 time in 12. Take out any single state and the solo operators as a share of all auto repair businesses pattern still holds.
• Weak spot: compare only states with similar median household income and the pattern keeps about 13% of its strength, so part of it may come from median household income instead of solo operators as a share of all auto repair businesses.
• For solo operators as a share of all auto repair businesses, of the 5 exception states, 2 read the same way for the other parts of the system (so that is the system there, not this repair) and 3 are specific to this repair.

Where more repair work is done by one-person operators with low overhead, prices and the kinds of repairs done differ from chain and dealer shops.

Source: Census Nonemployer Statistics 2021 and County Business Patterns 2023, NAICS 8111, joined to NHTSA owner complaints · file downloaded 2026-10-06