49 C.F.R. § 37.29 : Transportation — OFFICE OF THE SECRETARY OF TRANSPORTATION — TRANSPORTATION SERVICES FOR INDIVIDUALS WITH DISABILITIES (ADA) — APPLICABILITY — Private entities providing taxi service

(a) Providers of taxi service are subject to the requirements of this part for private entities primarily engaged in the business of transporting people which provide demand responsive service.
(b) Providers of taxi service are not required to purchase or lease accessible automobiles. When a provider of taxi service purchases or leases a vehicle other than an automobile, the vehicle is required to be accessible unless the provider demonstrates equivalency as provided in §37.105 of this part. A provider of taxi service is not required to purchase vehicles other than automobiles in order to have a number of accessible vehicles in its fleet.
(c) Private entities providing taxi service shall not discriminate against individuals with disabilities by actions including, but not limited to, refusing to provide service to individuals with disabilities who can use taxi vehicles, refusing to assist with the stowing of mobility devices, and charging higher fares or fees for carrying individuals with disabilities and their equipment than are charged to other persons.

49 C.F.R. §37.29