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Car comparisons

I can relate to the frustration that Jim Middleton expresses about the contradictory information that we are given about the pollution produced by cars of various ages.

Two years ago, Ford was claiming that a 1996 Fiesta produced only 5% of the pollution of a 1976 Fiesta. When I see comparisons like this my reactions are:

1) Are the cars both running on 1998 fuel? Even leaded petrol has changed dramatically in the last 20 years, and there is nothing to stop the owner of an older car converting it to run on unleaded. My wife and I drive mid-1970s cars, both of which have been converted. I am currently considering fitting a catalyst to one as an experiment.

2) Is the comparison made once the engine is warmed up, or when it is cold and the catalyst is not working?

3) What allowance has been included for the pollution caused by making the new car?

I drive around 10,000km a year, and use a variety of public transport, cycling and walking for my other journeys. Am I doing more or less damage to the environment than a sales rep clocking up an annual say 43,000km with a new car every two years?

Stephen King, CJ Sims, Essex House, 392 Rotherhithe Street, London SE16 1EF.

Driving display

It is good to see that the public debate on road traffic congestion/safety/pollution issues is taking place in NCE. Some interesting and sometimes amusing panacea have been put forward by several contributors.

My own is borne of experience driving a G-reg imported car equipped with a computerised fuel gauge.

This little gadget displays in sequence: tank contents in gallons; miles travelled since re-set; average mpg since re-set; and range in miles on fuel remaining.

I find myself choosing the mpg display and trying to maximise the reading by adopting an economical driving style. The effect is remarkable, with the fuel cost per mile ranging through a factor of three.

Even better than 'average mpg since re-set' would be a moving average over, say one to five miles

and a taxi-meter display of cumulative fuel cost on each journey. In this way, the direct cost of anti-social driving habits (and we all know what they are) will be plain both to the driver (you

know who you are) and his/her passenger(s).

The technology is trivial but the effect on safety and pollution could be significant. What we need

is a few electronic retro-fit kits and another compulsory tick-box on the MoT test form.

The answer to John Middleton's conundrum on fuel economy is surely that the emissions in the first reference are NOx, SO2, Pb and VOCs, while the second refers to CO2.

David Teal (M), Knight Piesold, Ashford,

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