Received wisdom is the knowledge passed down from generation to generation, often repeated but not always understood. To query these rock-solid foundations of knowledge is to invite scorn and disbelief.
Yet the world changes and, over time, what we take to be an article of faith must also change. It’s happened before in the off-roading world; automatics are no good off-road, coils aren’t strong enough for the bush… sounds strange, but those words would once have had you shot for heresy. Today we’re slowly coming to terms with independent suspension, some 16 years after the Pajero popularised it; 11 years after the introduction of the Discovery 3; and over 40 years since the Pinzgauer. And we’re also seeing electronic traction control erode the dominance of the cross-axle differential lock.
Now there is another assault on our dearest-held beliefs, and that is the death of the diesel.
Yes, I hear your cries. What? How? No! Madness! Sounds to me like the same sort of howling made by those manual-driving diehards not so long ago.
If you’re still here, I’ll justify my blasphemy. The first point is that all automotive development today is driven by one big factor above all others: Emissions. Specifically, the European Union (EU) emissions standards. Back in 1992 the first standard was passed, known as Euro 1. And now we’re up to Euro 6, as of September 2014.
Each iteration of the standards tightens the emissions requirements for diesel and petrol engines, and they apply to any model of car sold for the first time after that date. So for example, any car sold for the first time in the European Union after September 1st 2016 must meet Euro 6 standards. If a car is already on sale then it can continue meeting whatever standard was set when it was first on sale. There are different versions of Euro 6 for diesel and petrol, passenger cars vs light commercials, buses, trucks, and so on. There are similar standards – albeit not always as stringent – for other countries. The USA is largely driven by California’s requirements, but most other nations follow the current or older Euro standards (such as China, India, Israel, South Africa and yes, even Australia).
The second point is that cars are huge pollutants, and diesels moreso than any others. That is why their emissions are being curtailed so dramatically. Not only are the Euro standards reducing emissions, but recently a mass meeting of the C40 Mayors’ Summit saw the mayors of Paris, Mexico City, Athens and Madrid say they would remove diesel vehicles from their cities ‘as part of an unprecedented effort to improve the quality of air for their citizens’. Europe was long a lover of diesels, but now that tide is turning. European cities are introducing surcharges for diesels, considering banning them and generally turning against oil-burning internal combustion engines.
Why the diesel hate? That word again – pollutants. Nitrogen oxide (NOx) is a term for gases that contain nitrogen and oxygen formed when fuel is combusted at high temperatures, such as in an engine. The NOx gases are pollutants, and diesels make a lot of them. The Euro 3 standard in 2000 for diesel passenger cars allowed 500mg of NOx per kg; Euro 4 in 2005 was 250mg; Euro 5a/b in 2009/2011 was 180mg; and Euro 6 drops that right down to 80mg. Diesels also produce something nasty called particulate matter (PM), which is tiny particles of soot that hang in the air after combustion. PM is carcinogenic, which means it causes cancer – the International Agency for Research on Cancer lists PM as a Group 1 carcinogen.
Like I said, I could fill the rest of the Internet with the effects of diesels… but just know they’re evil. So why did Europe love them so? Because as we know, diesel engines use less fuel per kilometre than petrol engines, and petrol engines are actually worse on some emissions – specifically CO2 (carbon dioxide) and HC (hyrdocarbons). But because particulate matter and NOx are so very, very bad, overall diesel engines are worse for us and the environment than petrol engines. The recent advances have seen petrol engines improve their emissions and efficiency to a greater extent than diesels, too. The industry leaders considered diesel a dead technology even before VW ruined its reputation; Mercedes-Benz, HAVAL and Toyota have all indicated that they don’t see much of a future for diesel. Simply put, they can’t see a way to feasibly meet the increasingly-stringent emissions targets. Mitsubishi has killed the Pajero to focus on hybrid technology – I heard that direct from the president of the company. So, how does all this affect Australia?
Well, because we follow European standards (sort of) our diesels need to become cleaner and cleaner. This is a big problem for manufacturers, because it’s really tough to meet these standards. That’s why you see new or revised engines with barely any more power or torque… just improved efficiency or emissions. The Euro 6 standard will take effect in Australia for all-new models from July 2017 (and from July 2018 all new cars, whether all-new or not, will need to be Euro 6 compliant). That will knock out quite a number of vehicles on the market – exactly which ones we can’t say as there may be interim upgrades over the next 18 months – and particularly anything not ‘light commercial’ for which the standards are slightly relaxed. That’ll only drive more people to utes instead of wagons. However, we talked to a few manufacturers and they all have plans to be compliant at this stage.
But what are we, the touring off-roaders, going to do without diesels? We love our diesels because they are efficient under load, the high-compression engines provide good engine braking, the fuel isn’t flammable, the engine is simple and there’s lots of low-down torque. Diesels are better for off-roading; everybody knows it… right?
Not for much longer. As someone who reviews a lot of new cars and properly drives them off-road, I can tell you that there’s no significant capability difference between petrol and diesel. We live in an age of nine-speed automatics and high-compression petrol engines, so engine braking is adequate; and electronic hill-descent control is superb. Low-end torque is also extremely good, and petrol fuel efficiency is improving rapidly.
On the other hand, diesel is becoming far more complex. We have extremely high-pressure fuel injection with common-rail systems. We have exhaust gas recirculation (EGR), which reduces NOx by sending some exhaust gas back to the engine cylinders. There is the DPF, or diesel particular filter, which collects particulates and burns them off. And there is urea injection, with the best-known example being AdBlue – injections of a liquid into the exhaust gas to convert NOx to nitrogen and water. So the modern diesel is no longer simple, and it now always has a highly-sophisticated turbocharger (or two, or three) to go with it. Even worse, these EGRs, urea injection and DPF systems can fail – immobilising a vehicle that is in otherwise perfect working order. All three are just workarounds, tack-ons, extras to go wrong that have nothing to do with the engine’s basic job of delivering power or torque. That’s not what you want in your off-roader, is it?
So diesels aren’t simple anymore, their off-road performance advantage is nullified, and their efficiency advantage is being eroded. But there’s one more rather large nail to hammer into the diesel coffin – and that’s hybrid technology. That’s what will kill diesels in the next few years.
Petrol hybrids offer lots of low-down torque thanks to their electric motors; and better torque control than diesels too. They can harvest energy and reuse it, so their efficiency will (in the not too distant future) exceed that of diesels. Don’t believe me? Look at the three fastest road cars in history – the McLaren P1, Ferrari LaFerrari and Porsche 918 – all hybrids, and for reasons of performance.
Ah, but 4X4s are slow-speed, you say? Well, the Caterpillar D7E bulldozer offers a few lessons; that’s pure electric drive with the diesel engine only there to run the electric motor. Because of that the diesel can remain in its best torque and power bands, there are fewer moving parts, and Cat claims 10% productivity improvement and 10-30% better fuel efficiency. Look at electric chainsaws… unthinkable just a few years ago. And with electric drive at low speeds you can save the complexity and weight of a transfer case, too.
Welcome to the future. Your automatic transmission, independently-sprung, traction-controlled, petrol-electric hybrid, single-range 4WD awaits. Enjoy.