THE BURNING ISSUE: new car or golden oldie?

Buying or leasing a new car with greater frequency may allow you to drive a more fuel efficient and less polluting car, and therefore reduce your personal CO2 footprint, however it does not lead to a reduction in global CO2 emissions unless the old car is taken off the road. From a market perspective, increasing new car purchasing will lead to a flooding of the used car market, thereby driving down prices and leading to greater accessibility of car ownership. In crass economist language, effectively the new car drivers (economically advantaged) are enabling higher CO2 output of the (economically disadvantaged) used car drivers. Important variables in this discussion would also include when & how the car is driven, how far & how frequently it is driven, and at what passenger load capacity.

What about the energy used and pollution produced when manufacturing the new vehicle? If the old vehicle is scrapped, are you going to recover 100% of the material used in it? Can you recover 100% of the platinum in the exhaust for example?

Surely the answer is to have less cars, less parking/storing requirements, less energy and material use and build more compact cities (easy when you have narrower roads due to less parking requirement) and move people and goods by bicycle - now many here will not have experienced the movement of goods by bicycle and may have difficulties imagining it...
http://www.bakfiets.nl/eng/models.php
http://bakfiets.co.uk/

New or old cars are not the answer, and it is highly unlikely that they can be sustainable - unless you redefine sustainable... "sustain-washing"?

@Jennifer: I am not quite sure I agree withg that. Can you really expect individual buyers to pay a premium to do what is good for all of us, while the great majority of car buyers doesn't really care a lot? Until now, I think vehicles that perform substantially better and feature innovative technologies are very expensive: evebn while hybrid cars are supported by the governbment, diesel cars are much more economical (both in terms of mileage as well as over-all costs,.

Back to the topic: I think we need to use our cars much longer than we do now. Look at the actual improvements in terms of mileage: we haven't gotten anywhere really. Maybe ten years from now an average car may have 20-30% better mileage. Until then: just make sure you're an ecodriver and take the bus once in a while: makes much more sense. - Peter

If you can spare the money, buying a new vehicle regularly is the way to go. However, the best purchase policy for new vehicles is not only to make sure you buy the best performing option for this moment or even over its lifespan: it is important you invest your money in such a way that introduction of new technologies is stimulated (trigger car manufacturers to implement innovations!). It helps if the vehicle you buy is ready for future developments: e.g. can it cope with high ethanol blends? Does it feature hybrid technologies (which means it can potentially be retrofitted with a plug-in pack in the course of its lifespan)?