Most liberals I know who have bought hybrids do it to feel good and be trendy - the actual impact of replacing a servicable car with a new one is a huge environmental one - this excerpt from the New Scientist raises some of the issues and attempts to quantify..
Energy and Forces Transport 29 03 2003 Older model Given the energy required to make a car starting from raw materials is greater than it consumes in fuel, is it better to run "old bangers" for longer, rather than buying new fuel-efficient cars?
I read it takes more energy to make a car--starting from raw materials --than it consumes in fuel in its lifetime. Is this true? If so, shouldn't governments or environmentalists urge us to run "old bangers" for longer, rather than buying new fuel-efficient cars?
Russell Viner Wokingham, Berkshire
The precise answer to this question will depend on the individual. Take the example of a person running a really old gas-guzzler who considers switching to a new fuel-efficient model. This person would "spend" the energy that went into making the new automobile and save the energy that would have been wasted on less fuel-efficient travel in the old vehicle. Whether or not there will be a net future saving depends on the amount of energy needed to make the new vehicle, the difference in fuel efficiency of the two vehicles and the lifetime mileage the new vehicle will do. Opinions on the likely answers to this question and some added complications follow
Ed
An article produced by the US Institute for Lifecycle Energy Analysis compared the energy and toxic substance balances over the 14-year life of a mid-sized car made in 1990. It reported that, of the total energy consumed by the vehicle, only 10 per cent was due to the manufacturing process, whereas 82 per cent came from direct fuel use or was related to the fuel extraction and distribution cycle. The remaining 8 per cent was energy used for vehicle servicing, replacement parts and insurance and financial services. Interestingly, the toxic releases are split about 50:50 between manufacture and use.
The vehicle averaged the equivalent of 9.2 kilometres per litre. Most European cars will do better than this, yet they might only average a 12-year lifespan. These effects together could take the ratio of toxic releases between manufacturing and use to nearer 30:70, but the total energy consumed by the vehicle would still be overwhelmingly down to use rather than manufacture.
The institute's article concludes that if you can replace your car with one that is more fuel efficient the chances are high that you will reduce your overall energy impact. However, if you are more worried about toxic releases than fuel use, you should keep your old banger going for as long as possible.
Stephen Godalming, Surrey, UK
It may take more energy to build a new car than to run an older one, but this is probably not the concern of environmentalists nor governments.
Newer cars cause less pollution, and have a lower rate of fuel consumption. Therefore a fleet of new cars will save fuel and produce less pollution than the same number of older cars.
Also, while governments are interested in reducing pollution, they are also concerned with the nation's economy. A large amount of income and employment comes from the automobile industry, so keeping it active is in the nation's interest.
Finally, it is worth pointing out that the energy expended in creating new cars may come from a clean or renewable power source, such as nuclear or hydroelectric.
Sam Hariry Slough, Berkshire, UK
Governments are working on this. There are luxury item taxes on expensive cars that take more energy to produce than they will consume in their lifetime. In the US, there are federal mandates and penalties for car manufacturers to ensure they meet fuel economy goals.
In Europe, some governments require car manufacturers to take their vehicles back at the end of their lives and recycle the vast majority of parts, a cradle-to-grave mentality that could keep 99 per cent of the vehicle out of the waste product cycle.
We could probably close every mine in existence today if only we had a much more efficient recycling system in place. It takes less energy to recycle than it does to extract virgin materials from the ground. The reason we don't is because most consumers have not been sufficiently educated to form recycling habits, and most manufacturers don't yet produce goods that can easily be recycled.
Axel Ohmstede Arlington, Texas, US
For one thing, the 14 year life estimated for a typical car in the US is probably overstated imho.
, TAKE IT HOME WITH YOU! Hmm Hmm Good 
