This function takes a character vector of vehicle registrations (VRMs) and returns DVLA-based vehicle data from TfL's API, included ULEZ eligibility.
It returns a data frame of those VRMs which were successfully used with the TfL API. Vehicles are either compliant, non-compliant or exempt. ULEZ-exempt vehicles will not have all vehicle details returned - they will simply be marked "exempt".
Be aware that the API has usage limits. The function will therefore limit API calls to below 50 per minute - this is the maximum rate before an API key is required.