For the most part a "motor vehicle" is any vehicle which is required to carry PIP. It does not include a motorcycle. N.Y. Insurance Law 5102(f) defines a "motor vehicle" as:

(f) "Motor vehicle" means a motor vehicle as defined in section three hundred eleven of the vehicle and traffic law and also includes fire and police vehicles. It shall not include any motor vehicle not required to carry financial security pursuant to article six, eight or forty-eight-A of the vehicle and traffic law or a motorcycle, as defined in subsection (m) hereof.