Data Methodology & Sources

Every figure on AutoSpecData traces back to a named source. This page documents which source covers which data type, how values are derived, and where the limits are.

Primary sources

EPA / fueleconomy.gov — city, highway, and combined MPG, annual fuel cost, CO2 tailpipe grams per mile, fuel economy and greenhouse gas scores, engine cylinders and displacement, transmission, drivetrain, fuel type, and EPA vehicle class. These are official test results published by the U.S. Environmental Protection Agency and the Department of Energy.
NHTSA vPIC — the make and model universe used to structure the site.
Manufacturer documentation — towing capacity, tire size, and wheel fitment. These pages publish only where a verified figure exists; we do not estimate them.

Computed values

Maintenance intervals are computed, not copied. Each schedule is derived from the vehicle's recorded powertrain: fuel type, engine configuration, transmission type, drivetrain, and model year. An electric vehicle gets no oil service, a CVT gets a shorter fluid interval than a conventional automatic, all-wheel drive adds differential and transfer-case service, and vehicles from the synthetic-oil era get longer oil intervals than earlier ones. These are general intervals: your owner's manual is the authority for your specific vehicle, and severe-duty use shortens most of them.

Comparison and ranking pages are computed from the same underlying records — no separate dataset, no editorial reordering.

Freshness and verification

Each record stores the date it was last verified against its source, shown on the page as a "verified" badge. Records are re-checked when the source publishes new model-year data.

Known limits

EPA figures are laboratory test results. Real-world economy varies with driving style, load, terrain, and climate.
Coverage follows what the EPA publishes. Some trims, commercial vehicles, and heavy-duty models are not in the federal dataset.
Where a value is missing, the page shows it as unavailable rather than filling it with an estimate.

Corrections

Send corrections through the contact page. Include the year, trim, the value you believe is wrong, and the document you are comparing against.