Green NCAP LCA study shows detrimental climate and energy impact of increasing vehicle weight, including EVs
The results of the Life Cycle Assessment (LCA) of greenhouse gas emissions and primary energy demand of the cars tested by Green NCAP in 2022 show that the current and continuous trend towards larger and heavier cars, significantly increases the negative impact on climate and energy demand. This drives not only a rise in fuel and electric energy consumption, but also creates a wider footprint in vehicle and battery production.
Consumers and manufacturers share the burden for this trend given their steady interest in larger cars—in particular SUVs—as their vehicle of choice, commented Green NCAP.
Green NCAP tested 34 cars with different powertrain types: battery electric, hybrid electric, conventional petrol and diesel, and one vehicle, the Ford Puma, that runs on alternative fuel.
The LCA calculations used the interactive Life Cycle Assessment tool that is available for consumers on Green NCAP’s website. The calculations are made based on the average energy mix of the 27 EU Member States and the UK, and an average mileage of 240,000 km over 16 years.
These latest LCA results include further developments made on LCA methodology and data used. Compared to last year’s release, calculations consider the increasing share of battery production in Europe and use the forecast of energy supply in the period 2022‑2037. Furthermore, the vehicle maintenance model has been improved and among other points, now considers urea usage for diesel-powertrains.
Green NCAP uses the methods of Life Cycle Assessment (LCA) to investigate the total greenhouse gas emissions (GHG) and primary energy demand (PED) created throughout the entire life cycle of a vehicle.
LCA results from the 34 tested cars show that battery-electric vehicles are ahead in reducing greenhouse gases with 40‑50% less emissions compared to conventional gasoline cars, depending on the model chosen. In terms of primary energy demand, however, the differences between electric and conventional cars are less.
The hybrid electric sport utility vehicles (SUVs) that were tested, have higher fuel consumption and due to increased emissions in the usage phase, have life cycle values in the range of 200‑240 g CO2-equivalent/km and an estimated 0.85‑1.0 kWh/km. These numbers lie between the values of a large electric SUV and a conventional gasoline- or diesel-powered counterpart.
The bio-ethanol (E85) operated Ford Puma, as compared to the same car in gasoline mode, has greenhouse gas emissions reduced to a level closer to the range of battery electric cars. In this case, the processes needed for the bio-fuel production increase the Puma’s life cycle energy demand by 57%, yet given 60% of the total energy needed is renewable, much less fossil fuel is used.
Green NCAP said that these calculations show the considerable differences between each car’s impact on the environment, but they also reveal the significant influence of mass on greenhouse gas emissions and primary energy demand. This is clearly seen for all powertrain types even though the correlation might be slightly distorted for some cars due to differences in aerodynamic drag or powertrain efficiency.
Nevertheless, the overlying message is clear—the heavier the vehicle, the more harm it does to the environment and the extra energy required to drive the car. In general, battery electric vehicles emit significantly less greenhouse gases over their lifetime, but some of the gains are lost due to their increased weight.
Electric vehicles and electrification in general offer huge potential in reducing greenhouse gases, but the ever-increasing trend of heavier vehicles diminishes this prospect. To counteract this, Green NCAP calls on manufacturers to reduce the mass of their products and calls on consumers to make purchasing decisions that not only consider the powertrain of their new cars, but also consider their weight.—Aleksandar Damyanov, Green NCAP’s Technical Manager
To better illustrate how mass affects environmental performance, Green NCAP performed additional numerical simulations based on real-world Green NCAP measurements. These studies show that all three powertrain types (electric BEV, non-rechargeable hybrid HEV and conventional ICEV), when their mass increases, have the same relative rise in energy consumption of about 2% per 100 kg.
However, their absolute consumption figures are very different. Furthermore, higher mass is a major factor in the environmental impact of vehicle production. Based on today’s estimates, a net mass increase of 100 kg potentially results in an additional 500‑650 kg of GHG emissions and 1.9‑2.4 MWh of energy demand in vehicle production (without battery, including recycling).
Over the last ten years, the average weight of vehicles sold has increased by about 9% or around 100 kg. Sales of small SUVs have increased five times, becoming the most sold vehicles in 2022 with about four million cars sold across Europe. Large SUV sales have further increased seven times leading to a total sales number of roughly 700,000 cars.
Considering the impact of weight on consumption and on GHG and PED for production, for a compact family car, the 100 kg average increase in weight is responsible for about 1.4 tonnes of additional greenhouse gas emissions and 5.7 MWh of extra energy used.
According to the European Automobile Manufacturers’ Association (ACEA), in 2022, 9.3 million vehicles were sold, out of which 12.2% were battery electric. This leads to a revealing calculation—assuming eight million vehicles are on average 100 kg heavier, the impact of this weight increase on the climate is the equivalent of about 200,000 extra cars on European roads.
Green NCAP is an independent initiative which promotes the development of cars which are clean, energy efficient and cause as little harm to the environment as possible. Green NCAP uses a broad range of tests to address the flaws in regulatory approval tests and, through consumer information, rewards those manufacturers whose vehicles go beyond the minimum requirements and offer excellent, robust, real-world performance. Green NCAP’s tests are an addition and complementary to legislative requirements.