He said that eight pairs of cars were used in the tests, which revealed that petrol is not as good as diesel in terms of reducing NOx emissions when outside the standard cycle condition. The diesel increases its advantage in all other parameters when tested during acceleration at full load from 100km/h to 150km/h.
He added: 'It is accepted that the diesel gives out less CO (carbon monoxide) and HC (hydrocarbons) than petrol. Thanks to exhaust gas recirculation and the use of fuel with lower sulphur content, particulates can be cut by up to 50%.
'If only the oil companies would change the formula of the fuel and reduce sulphur content still further, particulates could be cut by an additional 30% for all vehicles presently in use. I maintain we could see so much benefit from particulate filters and improved 'cats' that the electric car would be useless. From 1960, we have divided diesel particulate emissions by 10. By the year 2000, they will be divided another four times. Diesels on the road then will be clean cars.'