For the past few years, though, diesel has been championed by an unlikely alliance of car-makers and environmental groups. Some environmentalists, citing the lower fuel consumption, have pointed to small, frugal diesel cars as the way ahead. And some European manufacturers, keen to push their environmental credentials - however mendaciously - have launched an advertising blitz on 'diesel is greener' lines. It has worked: diesels now account for about a fifth of new car sales in Britain, and the number is growing. Sales are booming on the Continent, too.
The Department of the Environment report, to be published in the autumn, apparently criticises diesels for their much higher levels of oxides of nitrogen, which can cause respiratory problems, compared with catalysed petrol cars. It also examines the carcinogenic properties of the fuel. For many years there have been allegations that the soot emitted by diesel cars can cause cancer.
Europe is the only major car market in the world where diesel sales are strong. In America even the low level of sales collapsed in the early Eighties, partly because of the difficulty in meeting Californian emission regulations, and partly because petrol is so cheap. In Japan, diesel has never caught on. Most of the major manufacturers there feel that the engine has no future.
But European manufacturers - especially the French - have been lobbying for greater tax advantages for diesel cars in all EC countries (in France and Italy, there is already a huge difference). They cite environmental benefits, but should fool nobody. If most Europeans bought diesel cars, Japan's challenge to the European market would be crippled.
To be fair to the French, they do build good diesel cars, and the best derv-drinkers of today are much better than those of even five years ago. The best French diesel cars are closer than ever to their petrol counterparts, in performance, quietness and smoothness.
Yet being almost as good as a petrol car to drive - and no matter how it is phrased, that is the best anyone has been able to say about diesels - does not seem a great commendation. Diesels are inherently rougher, noisier and less powerful. No amount of work by French engineers will overcome these drawbacks. They usually cost more to buy. True, they use less fuel, but when you look, smell or touch the stuff - and motorcyclists and bicyclists are forever falling off on spillages - the less frequent refuelling is often cancelled out by the sheer awfulness of the job.
LAST MONTH'S column, about my pet dislikes with modern cars - 'Faults that make me fume' - sparked more passion than anything I've written before. Plenty seems to annoy you about modern cars. A few examples:
Jane Hurley of Teignmouth, Devon, was not the only reader to criticise the difficulty in buying a car that can feed warm air to the feet and cool air to the face, simultaneously. 'I presume this is because most car designers are men and don't get cold feet in winter.'
John Stagg of London wishes modern cars were as comfortable as his old Austin 1800. 'The seats were set so high that it was not necessary to cripple oneself getting in and, especially, out, of the vehicle. The seats were also built so as not to contort the spine. I assume that modern car drivers like being permanently slumped, or perhaps once again it's those designer guys out to irritate the motorist.'
Eve Abbott of Bristol points out that many women have to move the seat forward to reach the pedals comfortably: 'This often results in being too much 'up under' the steering wheel and the seat belt sawing the side of one's neck.' Mrs Jean Keen of Sheffield says that when the seat is forward, the pedals are often at an awkward angle: 'In some cars, only the tip of my shoe can make contact with the pedal. Ford cars seem to be the worst.'
Valerie Moss of Ealing, west London, is fed up with hubcaps. 'My C-reg Peugeot 309 has lost four so far. It's a real nuisance having to get new ones.' (If car-makers would design decent-looking steel wheels, the damned things would be redundant.)
Many readers complained about the absence of flat surfaces on dashes - an impediment to storing odds and ends. Roger Whitehead of Church Stretton, Shropshire, writes: 'Ideally a flat surface and a lip: do car designers never need to put a book there or have an in-car picnic?' .
Kenneth Johnson of Moor Park, Hertfordshire, loves his Citroen ZX, but is annoyed that whenever the sunroof is open, there is an annoying interior hum. 'You can only cure it by opening the rear windows.' Mr Johnson says that he has had the same problem with earlier cars.
There were complaints about indicators that cancel too soon (especially on roundabouts), vulnerably mounted front number plates, and more. What is interesting is that readers weren't complaining about hi-tech, modern inventions. They are long-standing gripes, which the car industry seems intent to ignore.