2006 New York Code - Clean Air Taxis.

 
    19-533  Clean  air  taxis.  The  commission  shall approve one or more
  hybrid electric vehicle models for use as a taxicab within  ninety  days
  after  the  enactment  of this law. The approved vehicle model or models
  shall be eligible for immediate use by all current and future  medallion
  owners,  including  successful  bidders  for medallions sold pursuant to
  local law number 51 for the year 2003. For the purposes of this  law,  a
  hybrid  electric  vehicle  shall  be defined as a commercially available
  mass production vehicle originally equipped by the manufacturer  with  a
  combustion  engine  system  together  with an electric propulsion system
  that operates in an integrated manner.