Integrate a car rental broker API and handle insurance option complexity

Steps

1. Most programmatic car rental access goes through aggregator APIs (e.g. Rentalcars Connect, CarTrawler, Holidaycars API) rather than direct OTA APIs from individual rental companies; authenticate using your API key and partner credentials.
2. Search for availability by POSTing pickup location (IATA airport code or lat/lng), dropoff location, pickup datetime, dropoff datetime, and driver age (affects pricing in many markets); the response returns a list of vehicle categories with base rates.
3. Each result includes a rate_plan_id or rate_code — store this verbatim; booking requires passing it back unchanged, and rates can change between search and book.
4. Inspect the included_insurances[] and optional_extras[] fields: CDW (Collision Damage Waiver) and TP (Theft Protection) may be included in the base rate for some results but not others — surface this clearly before presenting a 'from' price.
5. Create the booking by POSTing the rate_code, driver details (name, license country, age), and selected optional extras; store the booking reference and the rental company's own voucher number separately.
6. Always surface the excess/deductible amount (the amount the driver is liable for even with CDW) — this is different from having no CDW at all, and many users confuse CDW with full coverage.