Vehicle weight standards can encourage vehicle manufacturers to produce lighter cars. Because lighter cars are more energy-efficient, they cause less CO2 emissions than heavier alternatives. Vehicle weight reductions can be achieved by, for example, re-designing or downsizing the vehicle, avoiding non-essential or luxury vehicle outfits and/or using lightweight materials.
Vehicle weight standards have not yet been introduced anywhere around the globe. Instead of weight standards, other regulatory mechanisms that encourage vehicle weight reduction could also be considered, such as credits (or debits) to manufacturers that meet vehicle weight or density thresholds.
Vehicle weight standards can complement existing vehicle fuel-economy standards or CO2 standards. This would be especially beneficial in places where existing standards are weight-based and therefore do not encourage vehicle weight reductions or may even encourage the opposite (i.e. as the stringency of the fuel economy/CO2 standard decreases with increasing vehicle weight). Whenever possible, vehicle weight standards should ideally be combined with any other measures that encourage the use of smaller, lighter vehicles, such as support for flexible car-rental/sharing schemes. As vehicle buyers tend to choose the specifications of their vehicle in line with what they may require for the occasional trip, many vehicles are oversized for most trips.
Weight standards would counteract past trends that showed increasing average vehicle weights. Such weight increases were due to consumer preferences shifting to larger, heavier cars in bigger vehicle segments (e.g. sports utility vehicles, or SUVs) as well as to weight increases within the same weight classes. For example, over the past four decades, the average passenger car weight has increased from around 1 000 kg to around 1 400 kg in the European Union. In emerging economies, the share of vehicles below 1 000 kg dropped from 28% in 2005 to 6% in 2017. From 2010 to 2015, the average vehicle registered globally increased in weight by more than 5%.
Studies have found that every 10% reduction in vehicle weight can cut fuel consumption and respective CO2 emissions by around 7%.
A study in the European Union also found that gradually reducing the average vehicle weight of cars from around 1 400 kg to 1 000 kg would result in cumulative CO2 savings of around 1 200 million tonnes (Mt) in the period from 2020 to 2050, or in savings of 85 Mt in year 2050. This is compared to a baseline scenario where vehicle efficiency improvements and the uptake of alternative fuel vehicles are not complemented with specific weight-reduction measures. In line with these findings, CO2 emission values for new cars would decrease from 78 gCO2/km to 56 gCO2/km thanks to the weight reductions.
Implementations costs of vehicle weight standards for public authorities can be expected to be similar to those of fuel economy or CO2 standards.
Costs for vehicle manufacturers to comply with weight reduction standards will depend on the size of the car and the weight reduction that has to be achieved, as well as on the cost of developing lightweight materials and components over time (which will depend on the demand for such materials/components). Recent cost estimates identified in the literature range from EUR 0.3 per kilogramme (kg) total weight saved (for a 10% reduction in total vehicle mass) to EUR 2.2 per kg (for a 30% reduction in total vehicle mass). Vehicle manufacturers may pass on increased vehicle costs to the consumer in terms of increased purchase prices.
For the consumer, increased vehicle purchase prices are likely to be outweighed by savings thanks to the reduced fuel use of lighter vehicles. A study found that vehicle purchasers and consumers could save EUR 262 billion from 2020 to 2050 if passenger car weights were reduced from the average of 1 400 kg to 1 000 kg in the European Union. Additional environmental benefits of EUR 100 billion would come from CO2 and pollutant reductions. Consumer savings alone translate to a negative cost (i.e. benefit) of around EUR 215 per tonne of CO2 saved.
Another study found that for an average current petrol car, there is a lifetime fuel-cost saving to the vehicle user associated with mass reduction of EUR 5.5 per kg. The absolute levels of cost savings per consumer depend on a number of factors including baseline vehicle mass, baseline vehicle fuel consumption, lifetime distance travelled and fuel prices. Other co-benefits of lighter vehicles were not considered in these cost assessments.
Next to CO2 savings, vehicle weight standards are likely to
With regards to safety benefits, a US study assessed the impact of US fuel economy standards (which also encourage vehicle weight reductions). It found that annually, the standards saved between 393 and 439 lives nationally, translating to USD 3.5 billion savings when using the US Department of Transportation’s value of a statistical life. This finding suggests that the fuel economy standards would pass a cost-benefit assessment based on the benefits from reduced fatalities alone.
It is important to consider:
Bento, A., Gillingham, K. and Roth, K. (2017) The Effect of Fuel Economy Standards on Vehicle Weight Dispersion and Accident Fatalities. https://environment.yale.edu/gillingham/Bentoetal_CAFEAttributesAccidents.pdf
Cheah, L. (2010) Cars on a Diet: The Material and Energy Impacts of Passenger Vehicle Weight Reduction in the US. Thesis. https://core.ac.uk/download/pdf/4427350.pdf
Cuenot, F. (2009) CO2 emissions from new cars and vehicle weight in Europe; How the EU regulation could have been avoided and how to reach it? https://www.sciencedirect.com/science/article/abs/pii/S0301421509005278?via%3Dihub
Cuenot, F. (2017) Wider, Taller, Havier: Evolution of light duty vehicle size over generations. GFEI Working Paper 17. https://www.globalfueleconomy.org/media/460880/gfei-wp17-ldv-global-vehicle-size-analysis.pdf
France stratégie (2019) Comment faire enfin baisser les émissions de CO2 des voitures? https://www.strategie.gouv.fr/sites/strategie.gouv.fr/files/atoms/files/fs-na78-2019-emissions-voitures-meilhan-20juin-bat.pdf
Idaho National Laboratory (INL) (2015) Vehicle Lightweighting: 40% and 45% Weight Savings Analysis: Technical Cost Modeling for Vehicle Lightweighting. https://avt.inl.gov/sites/default/files/pdf/reports/TechnicalCostModel40and45PercentWeightSavings.pdf
Institut fuer Energie und Umweltforschung Heidelberg (ifeu) (2016) Energy savings by light-weighting - 2016 Update. https://www.european-aluminium.eu/media/1878/ifeu-energy-savings-by-light-weighting-2016-update-full-report.pdf
International Council for Clean Transportation (ICCT) (2017) Foot versus mass: How to best account for weight reduction in the European vehicle CO2 regulation. https://theicct.org/sites/default/files/CO2-reduction-technologies_fact-sheet_10102017_vF.pdf
International Energy Agency (IEA) (2019) Fuel Economy in Major Car Markets: Technology and Policy Drivers 2005-2017. GFEI Working Paper 19. https://www.globalfueleconomy.org/media/708177/gfei-wp19.pdf
International Transport Forum (ITF) (2017) Lightening Up: How Less Heavy Vehicles Can Help Cut CO2 Emissions. https://www.itf-oecd.org/sites/default/files/docs/less-heavy-vehicles-cut-co2-emissions.pdf
Ricardo-AEA (2015) The potential for mass reduction of passenger cars and light commercial vehicles in relation to future CO2 regulatory requirements. https://ec.europa.eu/clima/sites/clima/files/transport/vehicles/docs/ldv_downweighting_co2_report_en.pdf
Transport and Environment (2008) Background briefing: Weight vs. Footprint - Weight-based standards make CO2 targets harder to reach. https://www.transportenvironment.org/sites/te/files/media/2008_04_footprint_background_briefing.pdf
Links
[1] https://www.itf-oecd.org/policy/vehicle-weight-standards
[2] https://www.itf-oecd.org/node/25144
[3] https://www.itf-oecd.org/node/26462
[4] https://www.itf-oecd.org/node/26463