Special Report on Diesel Motoring: On the road to a revolution: Sales of cleaner, greener diesel cars that offer reductions on fuel bills have risen by more than 13 per cent in the UK in two years. Martin Derrick reports

FOR YEARS the British market has lagged far behind the Continental markets in acceptance of diesel cars. The primary reason is simplicity itself: successive British governments have levied far higher duty on diesel fuel than other European governments and so - unlike in France, Italy, Spain and Germany - there has never been a clear-cut financial incentive to switch to a diesel-powered car.

Indeed, since company car benefit-in-kind scales were hiked in virtually every Budget of the late 1980s, Chancellors here were in effect adding a further disincentive, since one aspect of the formula upon which those scales rely is engine size and diesel engines tend to have a larger cubic capacity for a given power output when compared with a petrol engine - and hence more tax was levied by the Inland Revenue on the hapless company car driver who chose to drive a diesel.

Despite this, and despite the fact that in the past diesel-engined cars invariably had a higher list price than petrol-engined equivalents, there has for many years been a strong, if limited, following for diesel cars among drivers keen to benefit from the diesel's undoubted fuel economy. Also, since comparatively few new diesel cars were being sold, an equally small number of used examples were coming on to the used car market. Hence, by and large, used diesel car values have tended to be significantly higher than those for equivalent petrol-engined cars, and this in turn became in the eyes of the converted yet another good reason for buying new diesels.

For the vast majority of British car buyers, however, the diesel was rejected as slow, noisy, unrefined and smelly - and until recently, the manufacturers of diesel-engined cars were unable to dispute these perceptions for the awkward reason that they were entirely justified. Worse, since diesel fuel was available at only a minority of filling stations, the diesel car driver had to share a pump with commercial vehicles and suffer the filth that that entailed.

However, in recent years there has been a revolution, both in diesel car development and technology, and in the state of the market. And this development has been further fuelled by the realisation that, compared to a petrol engine, a diesel power unit is far kinder to the environment in terms of exhaust emissions. For those who still associate diesels with London buses and large trucks emitting vast clouds of choking black soot from the exhaust pipes, this might come as something of a surprise, but it is true: the diesel produces far fewer hydrocarbons and less carbon monoxide and - because of the greater fuel economy - less carbon dioxide, too.

The modern diesel car offers performance, noise levels, refinement and comfort on a par with petrol cars, yet still offers superior fuel economy to the tune of between 20 to 40 per cent. Little wonder, then, than according to the SMMT's figures, diesel car sales have risen by 13.3 per cent in the past two years, despite a drop in the total new car market of over 30 per cent. In 1989, 123,345 diesel cars were sold in a total market of 2.3 million units, while in 1991 the figure was 139,810 in a total market of 1.59 million. In 1980, fewer than 6,000 diesel cars found buyers in the UK.

All the signs are that the UK diesel market is going to continue to grow - though how long it will be before this market can match that of France, where last year 38.2 per cent of all new car registrations were diesels - remains to be seen.

First, there is now far wider choice available to diesel customers. Just in the last couple of years the 'traditional' diesel car manufacturers, Peugeot, Citroen, and to a less extent Ford and Vauxhall, have greatly increased the number of diesel variants on offer. Meanwhile new players - including Rover with the 200 Series and Metro, Seat with the Toledo and Volkswagen with the Passat - offer still more possibilities.

Second, in this year's Budget the Chancellor announced changes in fuel duty which have widened the differential between diesel and leaded petrol fuel prices. If and when there is greater harmonisation of fuel duty rates within the EC, the likelihood is that the UK's differential will widen still further as British Chancellors are forced to come into line with pan-European practice.

Third, the Chancellor also announced in the Budget a fundamental review of the whole company car taxation system. Meetings of the various interested parties have already taken place, and though no consensus has yet been reached, the one thing all are agreed on is that tax scales based purely on engine size discriminate unfairly against the diesel and make little environmental or fiscal sense. Change in this regard is certain and thus fleets will no longer be put off diesel because of resistance to drivers having to pay higher tax rates.

Fourth, the environmental question is not going to disappear. And it is a fact that the best of today's diesel cars are among the least polluting on the road. For example, Volkswagen's Umwelt Golf diesel substantially betters the strict US83 regulations: particulates 0.11 grammes per mile (0.20 = US83 regulations); carbon monoxide 0.08 (3.40); hydrocarbons 0.06 (0.41); and nitrogen oxides 0.82 (1.00). Because modern diesel engines mix more air with the fuel, they use and burn it more efficiently, combustion is more complete and nearly all the fuel in the cylinders is burnt away.

Overall, diesels emit less than one third of the unburnt hydrocarbons, 90 per cent less carbon monoxide and about 30 per cent less carbon dioxide than petrol engines. Whether as a result of further legislation, or due to consumer demand, the cleaner greener diesel engine is likely to attract still greater attention in the coming years.

(Photograph omitted)