‘Petrol and diesel have key advantages over electrification’
Battery and hybrid propulsion may be rising at the expense of traditional petrol and diesel, but they’re not going without a fight.
It’s a classic pincer movement. From one side, rapid advances in clean-running electric cars have propelled the likes of the VW ID3 and Jaguar i-Pace onto many buyers’ wish lists. From the other side, environmental concerns have made internal combustion engines look dirty and outmoded; the VW Dieselgate cheating scandal didn’t help one bit.
But, in fact, it’s not so simple. Viewed as part of a bigger picture, EVs aren’t as clean as you might hope. And the urgent need for car manufacturers to meet carbon-dioxide limits has prompted a rethink about low-CO2 diesel.
To guide us through this, two experts whose enthusiasm for cars is matched by their knowledge of different aspects of engineering. Bruce Wood is the managing director of the powertrain division of world-renowned Northampton-based Cosworth, while Prof Sam Akehurst, from the University of Bath’s Department of Mechanical Engineering, has over 20 years of automotive research experience, and works with several major UK-based car makers.
Bruce Wood (Cosworth): ‘The combustion engine is likely to remain a key element in future transport solutions for a long time to come. In the last few years electrification has come of age, and is now clearly part of the mainstream present and future solution. It has key advantages over engines – such as zero emissions at the point of use – but engines also have advantages, including the high energy density of fuel.
‘There is every reason to believe that over coming decades engines and electrification will sit side by side, often combined.’
Sam Akehurst (University of Bath): ‘Yes, the demise of the combustion engine is being exaggerated. Most predict there’ll still be 85 per cent engine-powered cars in 2030, without taking into account heavy-duty vehicles.’
BW (Cosworth): ‘Diesel has suffered a lot of reputational damage over recent years as a result of the fallout from Dieselgate, which is unfortunate as it has slowed development.
With the same level of development diesel will always offer higher thermal e ciency – and hence economy – over petrol, and in applications where this is paramount diesel will continue to have market share.’
SA (University of Bath): ‘Diesel has obviously got a bad press of late, but if you look at the latest engines their emissions levels are very low. The demonisation of diesel is particularly unhelpful when trying to meet CO2 targets. If you look at the fleet of diesel vehicles on the road they’re up to 10 years old; replacing those overnight with Euro 6-compliant ones would have a huge impact on emissions and fuel consumption and that opportunity has been lost to a degree by poor government intervention in the system.
‘The bigger split between diesel and petrol will be driven by cost. When looking at electrification and hybridisation, you’re looking at trying to take cost out of the engine and that’s more of a challenge with diesels than petrol. Bigger SUV-type vehicles might be diesel hybrids in the future, smaller cars will be predominantly petrol with mild hybridisation.’
BW (Cosworth): ‘Enabling an engine’s ancillaries to run on demand can offer a few percentage point improvements in thermal e ciency and is a significant area for development. There are options for electronic control of manual drives – such as clutching ancillaries in and out – or options for electric drive pumps, and both are already becoming more common.’
SA (University of Bath): ‘Diesel is pretty much near peak e ciency but by hybridising diesel engines they can be helped to operate at maximum e ciency.’
BW (Cosworth): ‘Come 2030, ’40 and ’50 you’ll most likely still be able to buy a petrol car. The world’s transport needs will become more diverse under the umbrella of the need to limit emissions. The solution will be the most appropriate motive power for each case. The combustion engine has a vital part to play alongside electrification.’
SA (University of Bath): ‘With a hybrid powertrain, we’ll definitely still see petrol engines in 2030, almost certainly in 2040, and probably in 2050. They will be different engines to today; as you progress through those decades they will be more like a range extender to help a more electrified vehicle.’
‘Diesel has su ered a lot of reputational damage, which has slowed development’