The question of whether to keep an old car or buy a new, cleaner car is difficult, with many important unspecified variables such as who 'owns' the emissions du

The question of whether to keep an old car or buy a new, cleaner car is difficult, with many important unspecified variables such as who 'owns' the emissions due to the manufacture of a car (the manufacturer? the first owner? all owners?). This isn't true for mileage though. If you move closer to work, your commute will emit less.