Do rough idle repair problems track quarterly job separations as a share of auto repair shop employment across states?

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

How to read it: Each dot is a state. Further right means more quarterly job separations as a share of auto repair shop employment; 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 quarterly job separations as a share of auto repair shop employment.

What it shows: States with more quarterly job separations as a share of auto repair shop employment tend to sit higher on the chart across 27 states: a pattern in the data, not proof of cause.

• The 9 states with the most quarterly job separations as a share of auto repair shop employment (Colorado, South Carolina, Tennessee, Georgia, Alabama, Arizona, Texas, Florida, North Carolina): reports of this repair run 16% above what the makes sold there would predict, and 8 of 9 are above expected. The 9 with the least (Massachusetts, Pennsylvania, New York, Illinois, California, Wisconsin, Maryland, New Jersey, Connecticut): 5% below, and 3 of 9 are above expected.
• Exceptions: Texas is among the highest in quarterly job separations as a share of auto repair shop employment but reports below expected.
• Split the states into thirds: the third with the least quarterly job separations as a share of auto repair shop employment runs 5% below what the makes sold there would predict, the middle third 8% above, and the third with the most 16% above. It steps up steadily.
• For quarterly job separations as a share of auto repair shop employment, after allowing for the 1562 comparisons we ran, luck alone would produce a pattern this strong about 1 time in 38. Take out any single state and the quarterly job separations as a share of auto repair shop employment pattern still holds.
• Weak spot: compare only states with similar auto repair shops per 100,000 registered vehicles and the pattern keeps about 49% of its strength, so part of it may come from auto repair shops per 100,000 registered vehicles instead of quarterly job separations as a share of auto repair shop employment.
• For quarterly job separations as a share of auto repair shop employment, of the 4 exception states, 2 read the same way for the other parts of the system (so that is the system there, not this repair) and 2 are specific to this repair.

Where shops lose and replace workers faster, fewer experienced technicians are available, which changes how repairs are diagnosed and redone.

Source: Census LEHD Quarterly Workforce Indicators 2024, NAICS 8111, joined to NHTSA owner complaints · file downloaded 2026-10-06