Dear Doctor Diesel,
I would welcome your thoughts on future legislation on diesel engines, i.e. talk of scrappage schemes, charging to go into town and city centres etc. I have been driving diesel engined cars for twenty years, and my present vehicle is a 55-plate Kia Sorento, with which we tow a caravan. As I am now retired, I had thought of purchasing a new vehicle, but am not yet settled on which make. Would you have any preferences on an SUV to tow 1,500kgs? My main concern is the extra cost of owning a diesel vehicle, plus that diesel fuel is more costly anyway, but I have no wish to return to petrol power. Your comments would be much appreciated.
John Gudgin

John, I think that there is a sufficiently strong ownership of existing diesels and power group in the form of the manufacturers that should resist too much immediate legislation – hopefully. What we have are two sets of EC regulations that are in conflict! The regulation of diesel emissions and the bias towards CO2 regulation is at the root of the problems. Manufacturers are often accused of being the problem but, much like with tax avoidance (which is legal) and tax evasion (which is illegal) they have done nothing illegal, or irresponsible. If the existing emissions testing regime, which has been tightened up progressively over two decades, is not controlling urban air quality, it is as a result of misguided regulation by the EC. If, as seems to be the main problem now, engines/cars that pass even the latest Euro-6 regulations are producing “real-life” emissions of particulates and oxides of nitrogen that are well in excess of those expected from the EC test cycles, that is the fault of the distinctly outdated test cycles, that are just not closely enough related to real life engine conditions, and for exactly the same reasons that the EC fuel data is not a true guide to real-life fuel economy. But there are issues that are not being addressed, as I see it. Recent tests that were publicised only recently in The Sunday Times, which has now started a campaign to get “something done about it” did not dig deep enough. Some cars that they tested in “real-life conditions” gave NOx emissions of up to six to nine times the EC limits, whilst others actually met the limits. There are two distinctly different systems used to control NOx – SCR or Selective Catalytic Reduction, using urea based additives that neutralise NOx (quite effectively, I believe, but I’ve not seen precise proof and test figures) and NOx storage and reduction, using an enriched fuel mix used at regular intervals to destroy temporarily stored NOx. If the varied test results just mentioned favour either of the above systems above the other in such real-life emissions tests, then this needs bringing to light, and measures taken to either insist on the better system being generally adopted – but along with new EC test cycles that can identify and actually measure the differences in real-life conditions, which the existing test cycles apparently don’t. If the results favouring some cars (and manufacturers) above others regarding control of NOx cannot be related to the differences between these two NOx control systems, then somebody, or some body, needs to get stuck in and identify the correct reasons. It cannot be a mystery, there are reasons, and they are there waiting to be identified!
But we’ve come a long way over recent years, we no longer see frequent clouds of black smoke bellowing from diesel exhausts, and we don’t (as I used to) travel behind some diesel vans without smoky or even visible exhausts that still left a choking feeling in your lungs. I don’t know for sure whether these figures of “up to 50,000 early deaths every year” from poor air quality related to diesel exhaust emissions are true, partially true, or maybe vastly exaggerated. If many of the people suffering from bad air quality are ex-60 a day Capstan Full Strength smokers, then the damage to their lungs was probably done long ago! This is not the time for knee-jerk reactions to this issue, but that’s precisely what governments tend to do.
So regarding your fears for future legislation, I can’t, I’m afraid, predict the future, because the future decisions may be neither logical, nor sensible. Regarding your choice of a vehicle, towing a caravan definitely shouts out get a diesel and, whether you buy a clean or cleaner one (but by what measure?), may not have any effect whatsoever on legislation or your freedom to use it, or the cost of using it. I would tend to ignore all the hoohah and just buy yourself a new diesel SUV.
Regarding which one, I’ve a tendency to lean towards something Japanese because their environmental laws and controls are among the most advanced on the global scene, and their cities are very clean. So maybe think Honda/Mazda/Toyota – although since these type of vehicles are not that popular in Japan, and are mostly made for export, I’m not that sure whether they clean them up as carefully as they would for their domestic market! If you did ever look at petrol power, you should look at the Mazda CX-5 2.0, which is good on fuel. I hope this gives you some useful thoughts John, but don’t be afraid to come back to me if you think that I might be of further help.
The Doc