Green NCAP aims to provide the most comprehensive independent information to consumers about as many vehicles as possible.

Until recently, the internal combustion engine was the only power unit readily available to car buyers. Petrol and diesel-powered cars have been around for decades and have become increasingly sophisticated, delivering ever-better on-road performance and improved fuel economy. From the 1990s, the diesel engine in particular became increasingly popular, with better fuel economy than petrol and lower carbon dioxide emissions. In recent years, the harmful effects of diesel engines have become apparent; some cities are banning, or proposing to ban, such vehicles from their centres and there has been a sharp drop in sales.

Green NCAP scope of tests

Car manufacturers are looking to electric propulsion to reduce the emissions footprint of the fleet. Hybrid vehicles have been offered for several years and, more recently, fully electric cars have emerged which promise to drastically reduce emissions from transportation.

Today, most new models are offered with a range of power units: petrol, diesel, hybrid and, sometimes, full electric. Petrol and diesel variants may be offered with a choice of power/torque outputs, most often achieved by different mapping. Green NCAP aims to provide information about as many of these variants as possible but it is almost impossible for an independently-funded organisation to test all of them. The most popular vehicle types, across the range of powertrain types will be tested, to try to maximise the information available to consumers. In time, as more cars are added, the database will expand to provide a comprehensive resource to individual car-buyers and to fleet managers. To begin with, Green NCAP will look only at passenger cars. The impact of goods and freight vehicles is recognised but is beyond the scope of the initiative, at least to begin with.

The most popular passenger vehicles types across the range of powertrain types are tested.

The testing and assessment of plug-in hybrid vehicles (PHEV) is very complex. To get representative and comparable figures, the state of charge of the battery must be known and incidences of battery charging recorded. Green NCAP is currently developing these testing procedures and will soon publish results for PHEVs.

Green NCAP scope of testing

Green NCAP’s tests currently involve the measurement of gaseous emissions in a range of different test environments, both in the laboratory and on the road. The tests therefore consider only the emissions generated by the vehicle once it is on the road. This is known as ‘tank to wheel’ assessment. However, on a global scale, other factors are important too. For petrol and diesel engines, the energy expended in extracting the fuel and delivering it to the point of sale is important; for electric vehicles, the energy ‘mix’ of the electricity used for charging the car is important – good if comes from renewable energy; bad if it comes from fossil fuels like coal. This measure of emissions is known as ‘well to wheel’. Ultimately, all of the energy that goes into producing the car in the first place should also be considered – a whole ‘life-cycle’ assessment. This is Green NCAP’s ultimate aim: to be able to inform consumers which vehicles are the least damaging to produce, operate and, at the end of their useful lives, to destruct and recycle. However, at the start, Green NCAP will focus on ‘tank to wheel’ emissions.

‘Tank to wheel’: the tests consider only the emission generated by the vehicle once it is on the road.

In the future, Green NCAP will also consider environmental factors such as noise – now proven to cause sleep disturbance, cardiovascular disease, elevated hormone levels, psychological problems and even premature death. So, the scope of the programme will grow rapidly in the coming years.

For a more detailed overview of Green NCAP’s proposals from now to 2030, look at our Roadmap in the “For Engineers > Technical Papers” section.