Before we all switch over to the hydrogen-based economy and the fuel cell becomes the green powertrain of choice for the automotive industry, there will be plenty of debate about the best and most environmentally sound powertrain solutions. How does diesel stack up against the gasoline-electric hybrid and where is diesel share heading? Rob Golding takes a look at some of the issues facing the proponents of diesel as well as the arguments put forward by one of the diesel engine’s biggest champions, PSA’s Jean-Martin Folz. 

It’s highly probable that diesel cars will represent more than half the market in Western Europe for the first time when the figures come in at the end of the year. It was 49% diesel at the halfway point and might have passed the landmark then had it not been for a shortage of particulate filters in Germany.

The remorseless onward march of diesel is the cause of rejoicing in some quarters. No-one is more pleased than Jean-Martin Folz, the chief executive of PSA Citroen Peugeot who sees every step forward for diesel as a step back for other (more questionable) short-term palliatives for global warming.

Folz is a mild and rational man but he is easily irritated by the ill discipline of researchers and legislators who cannot decide in which way lies salvation. As a consequence there is anarchy within legislation, the carmakers become cost-laden by diversity of national market requirements, and consumers and humanity are sold short.

That’s his view. The strength of his view leads him to passionate advocacy of diesel as the short-term (at least) solution.  There are some issues with particulates that render the fuel less attractive, in that regard, to gasoline. But known technology for particulate traps can generate a response to much tighter regulation. Issue solved. Let’s ignore hybrids and bio-fuels and get on with it.

Folz is right to try to focus minds on a single, simple measure to reduce emissions of CO2. It would be wise to remember that the development of diesel to its present (arguably) superiority to gasoline has been the work of more than half a century. It must be unlikely that a wholly new drive technology is going to deliver the goods in short order.

One legislative intervention that Folz will encourage – because it has worked very well for his company (and for France) in the past – is a programme of payments to owners of old, badly-designed and badly maintained cars which are 90% of the cause of the emissions problem. Encourage these cars to be surrendered and pay incentives to the owners to but a new one with far greener performance. Even if a ten-year-old car was still in its ‘as new’ condition”, its CO2 emission would be 12% worse than the equivalent new model according to figures from the European Commission. Of course, it wouldn’t be in ‘as new’ condition, would it?

This has been done before in France and works particularly well for the French vehicle makers because France is the most patriotic of all the major European markets. The principal beneficiaries of the bulge in demand for new cars would be Renault, Peugeot and Citroen.

What would give Folz particular pleasure is if all these artificially generated buyers of new cars were to opt for a PSA diesel-hybrid. He doesn’t actually make such a thing at the moment, but says that he is going to – just to end his irritation for the gasoline-electric hybrid which makes no real contribution to anything. He will be showing the technology installed in a car early next year to generate feedback.

“Only a diesel-hybrid system is attractive because it offers a real fuel consumption reduction,” said Folz.

London is a particularly good example of legislators distorting demand by muddled thinking. The gasoline/electric Toyota Prius has been exempted from payment of the London central area congestion charge simply because of the nature of its engine technology – not the result of its engine’s operation. With a following wind it can manage sixty miles to the gallon, but so too can the very best, modern diesels in a lightweight car. London is not the only example of anti-diesel discrimination.

To argue that gasoline-electric is better than diesel is to forget the additional weight of such a car and the additional energy consumed in the very expensive, extra-process, manufacturing stage.

Folz said there is no room for petrol-hybrid cars in Europe, where diesel engines are well accepted. Petrol-hybrids are better suited to countries where petrol engines dominate, such as the US and Japan, and where the culture and infrastructure still limits the potential for the growth of diesel.

In Europe, the growth is actually at its maximum. The 4% annual growth, that has taken the percentage diesel penetration from 30% to near 50% in less than six years, is stretching the capacity of the fuel suppliers to ride the trend. They have to build capacity to keep up and there is a very real danger that there will be a shortage, a price rise and a trend reversal.

There has to be some C02 reducer that is championed by legislators and carmakers alike, while we wait for fuel cells to ride to the rescue. The first commercial offer of a hydrogen car is ten years away at least. Even then the supply of them will be limited because they will almost certainly still be unprofitable for the producers. At the moment the production costs of a fuel cell is estimated at the same as a Formula 1 engine – around $1m. The only reason that they will appear at all is that manufacturers are very keen to build positive PR from the green credentials. Toyota has earned disproportionate benefit from selling its initial Prius cars at below manufacturing cost. They, and others, will do the same to support the first few years of fuel cell.

The most dependable estimate for an on sale date of 2015 is probably Toyota’s given that this is the company that stuck at the Prius development to grind the production price down to the point where the conspicuously-green consumers were prepared to pay the (subsidised) asking price.

Toyota says that it has “hundreds of engineers working away” on fuel cells. DaimlerChrysler meanwhile has sixty or so evaluation fuel cell vehicles already in service and gathering operating statistics.

It does therefore seem that diesel will be driven very hard for the next ten years to assist with bridging the gap to 2015. Consider the ground that has been covered in the last 10 years and the contribution diesel transition can still make in that time is considerable.

Around Europe, the progress has been very varied. Because they have been catching up frantically, the smaller countries such as Norway and Switzerland turned in diesel market share growth performances of 338% and 314% respectively, according to figures published by Auto Industry Data.

Belgium and Spain, which had already reached just over 50% market share for diesel, showed that there is still life after half-and-half, and moved on to 72% and 67% respectively. Of the Big Three markets, the UK was the star performer. Its market share was up 180% over the period, while Germany doubled and France was up 60%.

In the US – where fuel economy was an expression of concern last heard before the Bush administration took office – there are 40,000 diesel-engined cars in total. That’s it. Ricardo, the UK engine specialist, estimates from various industry bodies that it will take another three years to break 100,000 and six years to get through a million.

Diesel and gas cost the same in the US, so the roadside billboard prices don’t do much to provoke change. All the economic incentive therefore is in the greater fuel economy, and when percentage increases are built from a very low base the benefit is not all that compelling. A 30% improvement in changing from gas to diesel in the UK can be 10mpg or more. In the US it might be three. In the UK, diesel converts actually have to overcome the obstacle of diesel fuel costing up to 7% more before looking at the 30% fuel saving. On average though, diesel fuel prices in Europe are cheaper than petrol.

But there are some movers and shakers in the US. Delphi and Bosch, the two lead players in the diesel component business, are both making huge investment in diesel engineering research centres in the US and are laying down production plant. Amongst the carmakers, Volkswagen and Mercedes are the first to have diesel cars on sale. Volkswagen is going for the premium models in the mid range. Mercedes has so far fielded an SUV and an S-Class. Because of the vicious price battles at the low-end of the price range in the US, diesel has to try to make an impact higher up the price range where the additional production cost of a diesel engine – still more than $1,000 – is easier to absorb.

There is no easy way of escaping the cost of providing items not required in the petrol engine. The expensive items are the turbocharged intercooler, high-pressure common rail direct injection, particulate filters and measures to remove noise, vibration and harshness (NVH). Commercial light trucks and minivans are the more obvious first target for diesel, but that market is still minded to look at purchase costs rather than operating costs.

There is yet a tank trap down the road for diesel planners. Draft so-called Euro V rules designed to clean up car exhausts are tough, possibly too tough and therefore counterproductive according to the industry.

The European Commission has been warned that for the diesel industry to meet the new levels, engines would have to cost as much as €1,500 more than they do now according to the European Association of Vehicle Manufacturers. That could form sufficient of a deterrent on purchase price to reverse the diesel movement and the benefits thereof. It sounds like another case for the crusading Jean-Martin Folz.

Rob Golding

This feature has been sponsored by ArvinMeritor – leaders in diesel emissions technology. To learn more click here