Do brake booster replacement problems track share of households with three or more vehicles across states?
Across U.S. states, NHTSA owner complaints about brake booster replacement run higher where share of households with three or more vehicles is higher, after adjusting for the makes sold in each state. This is an association across states, not proof that share of households with three or more vehicles causes this repair.
State reports of this repair against share of households with three or more vehicles, one dot per stateEach dot is a state: how much more (or less) than expected this repair is reported there, adjusted for the makes sold in the state, against its share of households with three or more vehicles
How to read it: Each dot is a state. Further right means more share of households with three or more vehicles; 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 share of households with three or more vehicles.
What it shows: States with more share of households with three or more vehicles tend to sit higher on the chart across 31 states: a pattern in the data, not proof of cause.
Data: U.S. Census Bureau, American Community Survey 5-year 2019-2023, counties summed to states (B25044), joined to NHTSA owner complaints, downloaded 2026-10-06 · 31 states. Chart: CalcScrape · calcscrape.com
The 10 states with the most share of households with three or more vehicles (Utah, Kansas, Washington, Alabama, California, Tennessee, Virginia, Colorado, North Carolina, New Mexico): reports of this repair run 12% above what the makes sold there would predict, and 8 of 10 are above expected. The 10 with the least (New York, Massachusetts, Florida, Louisiana, New Jersey, Illinois, Pennsylvania, Michigan, Connecticut, Ohio): 8% below, and 3 of 10 are above expected.
Exceptions: Alabama and Tennessee are among the highest in share of households with three or more vehicles but report below expected.
Split the states into thirds: the third with the least share of households with three or more vehicles runs 8% below what the makes sold there would predict, the middle third 18% above, and the third with the most 12% above. Most of the share of households with three or more vehicles effect sits between the lowest and the middle third.
For share of households with three or more vehicles, after allowing for the 1562 comparisons we ran, luck alone would produce a pattern this strong about 1 time in 19. Take out any single state and the share of households with three or more vehicles pattern still holds.
Weak spot: compare only states with similar vehicles per household and the pattern keeps about 0% of its strength, so part of it may come from vehicles per household instead of share of households with three or more vehicles.
For share of households with three or more vehicles, of the 5 exception states, 3 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.
In households with three or more vehicles each car is driven less and sits more, which rusts brakes, flat-spots tires and drains batteries.