Diesel has come a long way but still doesn't get the tax breaks it deserves

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DUDLEY Noble was a silver-haired septuagenarian by the time I knew him, but in 1913 he was sent by Rover to Harwich, to meet the overnight ferry from Antwerp. Rover was not having much luck with Knight sleeve valve engines. It wanted to try the new compression ignition engine from Germany.

Noble had been despatched to meet the celebrated Dr Diesel. He had a photograph of the famous engineer, a letter of introduction, and instructions to bring him to Coventry. He waited in the cold light of an autumn dawn, at the Harwich customs shed, alas in vain. Rudolf Diesel had been on the cross-Channel packet, SS Dresden, but his cabin was empty, his bed not slept in, and he was presumed lost overboard.

Did he slip or was he pushed? Diesel’s engine had applications well beyond any Rover had in mind. Electric motors were the only practical motive power for a submerged submarine. Anything else produced heat, fumes, and exhaust gas. Petrol engines had been used to charge the batteries, and propel the vessel on the surface, but in February 1906 a U-boat of the German fleet was destroyed by fire when refuelling.

The answer was diesel. The fuel had a lower flash point, less was lost through evaporation, it was more economical, and so the submarine had a longer range. The French and Russian navies were building diesel-engined ships, but in May 1908 Britain was first with a diesel submarine, the D.1 launched at Barrow. The First Lord of the Admiralty, Winston Churchill, sailed proudly on it out of Portsmouth.

With an eye on the menacing German fleet, Churchill was eager to match its submarine-building programme, but found "... great technical difficulties, and the delays of the contractors are vexatious in the extreme".

Dr Diesel’s engine was of great strategic importance. In 1911 Germany laid down U19 with twin diesels, so it is likely that the Kaiser’s government was less than happy at the prospect of Diesel sharing secrets with the British Admiralty. It is equally possible that Diesel’s disappearance in the Channel could have had something to do with Krupp. The German shipyard had a new interest in exporting U-boat technology. In 1914 Jane’s Fighting Ships carried an advertisement featuring a submarine Krupp built for the Italian navy. It looked like an invitation to meet the technical difficulties, replace the contractors that so worried Churchill, and with Dr Diesel on the loose the First Lord might get the help he needed more or less free.

We shall never know whether it was cloak and dagger work by the Kaiser’s secret service, industrial espionage on a grand scale, a depressive mood following another failure of his fuel injectors, or the heaving deck of a cross-Channel packet-boat that deprived the world of Rudolf Diesel, together with the plans in the briefcase that vanished with him.

Diesel’s earliest experiments were not with fuel oil but with injected coaldust. It should have been a more efficient way to generate steam than shovelling coal into furnaces. In the event the experiment was not a success, and Diesel had to fall back on the 1890 work of Herbert Ackroyd Stuart, who patented an oil-fired engine for Richard Hornsby & Sons of Grantham, Lincs. One was sold to Newport Sanitary Authority, but the compression ratio was too low to get it started from cold, and it needed a heat poultice to get it going.

A Hornsby-Ackroyd Patent Safety Oil Traction engine was sold in 1897 to Hugh Fortescue Locke-King, builder of the Brooklands race track near Weybridge, probably to use as a generator. Hornsby advertised four sizes of engine, between 16 and 30 horse power, but no more seem to have been sold. Yet in at least one respect Ackroyd Stuart’s engine was closer to the modern compression ignition engine than Diesel’s. It injected fuel into the cylinders by means of a plunger pump. Diesel relied on a high-pressure jet of air, a system whose shortcomings frustrated him for the rest of his life. It is really something of an accident of history that the generic name for the power unit turned out to be diesel and not ackroyd stuart.

Compression ignition still has virtue. The fuel is less explosive, less is lost through evaporation, diesel engines are more economical, and the same size of tank takes you further. The commendation that they dispense with electricity, always a bother in engines, unfortunately no longer applies. Electronics now monitor the fuel injection system and when components fail, as one did recently on my Nissan, its replacement cost 500.

Diesel should be encouraged on the grounds of good national housekeeping. You get more miles out of a barrel of oil if you refine more of it to diesel, than if you purify it to petrol. Yet not only do we have expensive diesel fuel, but, almost alone in Europe, it costs more than petrol. It is only in Switzerland and the UK that customers pay extra for diesel instead of the other way round. The difference is that in Switzerland it is 63p a litre; here, on the AA’s average figures for January it is 77.5p.

Europe’s cheapest diesel is Luxembourg’s at 42.94p a litre. In the US it is 26.04p a litre.

Since the introduction of low sulphur fuel, diesel no longer attracts a higher rate of tax than petrol, but under current company car tax rules, a 3% surcharge is added to drivers who choose diesel, despite its advantages in emissions. Diesels produce 15% less CO2 than petrol engines, approximately 1% of the CO, and only one-third of the hydrocarbons of those remaining cars without catalytic converters.