Use the fueleconomy.gov Web Services API to populate a year, make, and model vehicle picker and retrieve official EPA fuel economy ratings for the selected vehicle

Steps

1. Call the vehicle menu endpoints in sequence, retrieving available years, then makes for a selected year, then models for a selected make and year, to drive a cascading vehicle picker
2. Call the options menu endpoint when a single make and model maps to multiple trims or configurations, so the user can select the exact vehicle variant
3. Retrieve the full vehicle record for the selected option ID to get combined, city, and highway MPG figures
4. Parse the response in the XML format the service returns by default, or convert it as needed for your application
5. Cache menu and vehicle record responses locally where appropriate, since the underlying EPA dataset only updates with new model years rather than continuously