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The King Review of low-carbon cars – ten years on

Professor Richard Folkson CEng FIMechE President, Institution of Mechanical Engineers 2015-16

Electric cars could account for a 30% reduction in carbon dioxide emissions by 2030
Electric cars could account for a 30% reduction in carbon dioxide emissions by 2030

Ten years after the publication of the King Review of low-carbon cars, prepared by Professor Dame Julia King, then Vice-Chancellor of Aston University, it is appropriate to consider how much progress has been made towards the vision set out in the Review.

The main recommendations contained in the report, forecast a wholesale switch to electric cars powered by electricity generated from renewable sources. Professor King saw this as the best solution for decarbonising road transport and eliminating tail-pipe exhaust emissions, particularly in urban environments. The review was well received by the UK Government of the time and steps were taken to encourage the adoption of electric cars. Most significant of these was a £5,000 customer incentive against each new electric car sold. There was also a substantial amount of money spent on providing the recharging infrastructure for electric cars across the country, but with concentrations of charging points in London, the East of England, the Midlands and North East (particularly around the Nissan car plant). The King Review forecast that a 50% reduction in carbon dioxide emission levels from vehicles, to those in 2000, would be possible by 2030, using a mixture of electrification, hybrid drive and more-efficient powertrain technologies. It also said that the complete decarbonisation of road transport may be possible by 2050.

The impact of the King Review on electric car sales

There have been many additional factors affecting the take-up of electric cars since the King Review was published, and several of these have reduced the rate of adoption significantly. Firstly, electric cars remain very expensive to purchase compared to conventional internal combustion engine powered vehicles. Typically an electric car costs about double the price of a conventional car and even with the £5,000 cash incentive against the purchase price, it takes a very long time for consumers to recover the additional cost from reduced fuel bills. Despite increasing sales, Tesla and Nissan continue to make substantial losses on the manufacture of electric cars.

The economic challenge for electric cars has been exacerbated by a significant fall in the real world price of fossil fuels over the past ten years. This has been the result of average reduced fuel consumption in new cars due to improved efficiency of internal combustion engines, combined with oversupply of crude oil and aggressive pricing strategies from the Gulf States. Overall, crude oil prices have dropped from a peak of about $100 per barrel to a little over $50 a barrel today.

Although electric cars are now selling in much greater numbers than in the early years after the report was published, the overall volume remains orders of magnitude lower than the sale of conventional cars. There are now a large number of electric cars available on the market selling in reasonable numbers, such as the Tesla Model S which retails at about £80,000 and the Nissan Leaf selling for up to £30,000, both roughly double the cost of a conventional car in the segments in which they compete. Electric cars are also manufactured by Renault, VW, Audi, BMW, Mercedes-Benz, Ford, General Motors (Chevrolet), Kia and Hyundai. Tesla has added several new models with the recently launched Model X and Model 3, which will increase the appeal through lower-priced cars.

The market for electric cars has started to see substantial growth, particularly in the last few years, from an almost negligible percentage in 2013 of 3,500 cars to a share of 1.6% in 2017, representing about 108,000 plug-in cars charged from the grid. However, this is still a very slow growth over the ten years since the report was published, compared to the 2.69 million new cars sold in the UK in 2016. Electric car sales are up about 50% in 2017, but still represent less than 2% of the total.

Other factors

The Volkswagen emissions scandal of 2016 has had a major impact on perceptions of diesel engine emissions and the manufacture of internal combustion engines. This has also shifted the emphasis away from just carbon dioxide emissions to other pollutants such as NOx and particulates. However, despite the current anti-diesel sentiments and proposals to eliminate internal combustion engine driven cars entirely by 2030, diesel sales in the UK still account for about 50% of all new cars. However, this does not mean the end of the internal combustion engine in the near term, but rather that there will be a trend towards more hybridisation and a mix of fuel-efficient, low-emission petrol and diesel engines used in conjunction with varying degrees of electric and battery propulsion. Series hybrids with small IC engines driving a generator to add range to the battery pack, probably offer the best opportunity for improved emissions and economy. Mazda recently announced that the emissions from its latest petrol engine technology, can match the lifetime emissions of an electric car that uses electricity from fossil fuel sources. Large-scale adoption of electric cars charged from the grid will also present major challenges for infrastructure and charging capacity/load factors. 

Autonomous driving cars are expected to add to the demand for electric cars, as the combination of electric drive with self-driving capability will be easier to deliver than the more-complex control strategies required for internal combustion engines.

Hydrogen fuel cells are starting to emerge as an alternative to battery electric cars but remain an even smaller sector, with fewer than 100 vehicles in the UK in total, with Toyota leading developments into mass production of hydrogen powered cars. Fuel-cell cars are likely to cost three times more than a conventional car in the medium term, due to the cost of producing the vehicle’s hydrogen fuel storage tank.


The King Review predicted that electric cars could account for a 30% reduction in carbon dioxide emissions by 2030. The report was extremely well considered and technically credible, but the rate of electric car adoption has been slower than anticipated. The two principal reasons for this are the relatively high cost of batteries with adequate range in electric cars, and the continued improvements in petrol and diesel engine technology. Cars that make use of the internal combustion engines have continued to reduce carbon dioxide emissions and deliver improvements that are close to those achieved by electric and hybrid vehicles at significantly lower cost, particularly when factoring the reduced price of fossil fuels. The challenge for electric-car technology will be a breakthrough in lower-cost batteries with greater energy storage to deliver a driving range of about 200 miles. Until that is possible, internal combustion engines will continue to play an important role in car propulsion, and that may be for the next 20-30 years.

Professor Richard Folkson CEng FIMechE, President, Institution of Mechanical Engineers 2015-16 and a Former Chief Engineer, Ford Motor Company Limited.


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