I have brought a new car, it falls in to Band E for road tax.
It has a 1.6 engine, I have just looked ford focus web site two (out of three) of their 1.6 engines fall into band D.
It follows therefor my car pumps more carbondioxide, and water into the air, This is because my engine is fully combusting more fuel than the foucs. This means I realse less Carbon monoxide and unburnt hydrocarbons into the atmosphere.
If I am not mistaken carbon moxiode is a killer as it binds to heamoglobin, and prevents red blood cells transporting oxygen.
Some hydrocarbons are suspected to cause cancer, for example Benze.
If I am not mistaken trees need carbon dioxide to use in pohotsynthiesis, and produce food etc.
Water is usefull 1) for photosynthesis 2) There always seems to be a shortage in this country.
I hate the way people only seem to think about carbon dioxde and not the other crap cars can give out.
My car looks better too.

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Oct 11 Birmingham Half Marathon. I am running for the British Heart Foundation.
http://www.justgiving.com/Rob-Taylor