Guides

How to read complaint counts, MPG and crash ratings

Updated 2026-10-27

DecodedCars puts three kinds of public data side by side. Each is useful, and each has limits worth knowing before you compare cars.

Owner complaints

Anyone can file a vehicle safety complaint with NHTSA. DecodedCars counts every vehicle complaint received since 2015, once per report, grouped by model year and by the component the owner selected.

Keep in mind:

  • Popularity inflates counts. A model that sold 300,000 units a year will collect more complaints than one that sold 20,000, even if it is more reliable per car. Compare model years of the same model, or look at which components dominate, rather than ranking unrelated cars by raw totals.
  • Complaints are unverified. They are what owners reported, not confirmed defects.
  • Older model years have had more time to accumulate reports. A one-year-old model with many complaints is a stronger warning sign than a ten-year-old one with the same number.
  • “Typical mileage at failure” is the median mileage owners reported — useful for seeing whether problems show up early or late.

Fuel economy (MPG)

MPG figures come from the EPA’s standardized lab tests, adjusted to reflect typical driving. They are designed for comparing cars with each other, not for predicting exactly what you will get. Your results depend on speed, climate, terrain, tire pressure, cargo and driving style.

DecodedCars compares each version’s combined MPG with the average for its EPA size class and model year (for example, all 2024 midsize cars), so you can see whether a car is efficient for its type. Electric vehicles are compared by EPA range and energy use (kWh per 100 miles) instead.

Annual fuel cost is EPA’s estimate for 15,000 miles a year at current national average prices, which makes gas, hybrid and electric running costs directly comparable.

NHTSA 5-Star Safety Ratings

NHTSA crash-tests new vehicles and publishes ratings for frontal crash, side crash and rollover resistance, plus an overall score from 1 to 5 stars. A few things to know:

  • Ratings from 2011 onward use a tougher test program and cannot be compared directly with earlier ratings.
  • Ratings are specific to a body style and drivetrain — a 2-door and a 4-door of the same model can differ.
  • Rollover risk is the estimated chance of rolling over in a single-vehicle crash; lower is better.
  • Not every model is tested every year. “Not rated” does not mean unsafe.

All figures come from public NHTSA and EPA records. Comparisons, averages and rankings are calculated by DecodedCars.