From the HS2 thread, I thought it a point worthy of discussion. Car ownership is a lifestyle choice which in most cases doesn't make financial sense on its own. Car use can be deterred if other modes are good, e.g. good cycling/walking facilities and good public transport. If you want to reduce car ownership to zero in a given household, you need to look at measures that will make one easily available when it is needed e.g. for transporting "stuff" or for weekends away to places not well served by public transport or where you need a lot of kit (note: hire companies that don't open late Sundays and don't do unsupervised returns don't count; this alone makes hire useless to me in MK). Car clubs are a good example. You can reduce to 1 if public transport/cycling/walking is good enough, though.