Two field studies revealed large differences among various subgroups in the population of car drivers. Private drivers, commuters, and business drivers differed strongly with respect to current decisions and behaviour which affect CO2 emissions, and with respect to their sensitivity to various policy instruments. Several promising policy targets were identified" combinations of user groups and behaviours where substantial CO2 reduction may be achieved. The sensitivity of different car user groups to various policy measures showed whether and how desired behavioral changes may be realised.
