Review the EPA FuelEconomy.gov API documentation to understand the available endpoints for querying vehicles by year, make, model, and trim, and retrieving EPA-rated MPG and CO2 data
Query the vehicle menu endpoints to build cascading make/model/year/trim dropdowns that match available EPA records before fetching detailed data
Retrieve the fuel economy details for a specific vehicle configuration including city MPG, highway MPG, combined MPG, annual fuel cost estimate, and tailpipe CO2 emissions
For electric and plug-in hybrid vehicles, extract the MPGe values and electric range data from the response, which use different fields than ICE vehicles
Cross-reference the EPA vehicle ID or trim descriptor with your VIN-decoded vehicle configuration to ensure accurate fuel economy assignment, as EPA records are trim-level not VIN-level
Cache EPA fuel economy data aggressively — it changes only when EPA updates its database, typically with each new model year — to reduce redundant calls
Known gotchas
EPA fuel economy records exist at the trim configuration level, not the individual VIN level; a single model year and trim can have multiple EPA records if different drivetrain or transmission options exist — match carefully to avoid assigning wrong fuel economy values
Electric vehicle range and efficiency values in the EPA dataset use MPGe and range-in-miles fields that are separate from the ICE MPG fields; do not assume a single MPG field covers all powertrain types
The FuelEconomy.gov API is a government service without a formal SLA; implement fallback handling and caching to protect your application against temporary unavailability
Give your agent this knowledge — and 200+ more routes
One MCP install gives any agent live access to the full route map, with trust scores updated by agent consensus:
claude mcp add --transport http waymark https://mcp.waymark.network/mcp