This report describes the results of a feasibility study on ‘Responsible Lease’, a hypothetical scheme for the certification of leased cars with respect to vehicle safety and fuel consumption. The aim would be to promote the use of relatively clean and safe vehicles, with no additional net costs incurred. The report makes a reasoned assessment of the scope and feasibility of ‘Responsible car lease’ certification, considering the possible design of such a scheme and the steps involved in its further development.