40 CFR § 88.308-94
Programmatic requirements for clean-fuel fleet vehicles
June 9, 2020
(a) Multi-State nonattainment areas. The states comprising a multi-State nonattainment area shall, to the greatest extent possible, promulgate consistent clean-fuel fleet vehicle programs.
(b) Program start date. The SIP revision shall provide that the clean fuel vehicle purchase requirements begin to apply no later than model year 1999.
[59 FR 50082, Sept. 30, 1994, as amended at 63 FR 20107, Apr. 23, 1998]