The study compares official and “real-word” fuel consumption and CO2 emissions for passenger cars in Europe and finds that the average discrepancy between them rose from less than 10 percent in 2001 to 25 percent in 2011.
BMW’s reported emissions are about 30 percent below real-world numbers while Audi’s gap is about 28 percent, the study says. Toyota’s fuel economy figures are 15 percent lower than its real-world performance.
The report says automakers haven’t done anything illegal. It says the growing gap between actual and reported emissions is likely due to several factors including:
- Increasing application of technologies that show a higher benefit in type-approval tests than under real-world driving conditions, such as start-stop technology.
- Increasing use of flexibilities, or permitted variances in the type-approval procedure, for example, during coast-down testing.
- External factors — such as increased use of air conditioning — changing over time.
The ICCT says the gap widened after 2007–2008, when several European Union member states switched to a CO2-based vehicle taxation system and the EU introduced a mandatory CO2 regulation for new cars.
The difference between reported and real-world efficiencies halves the expected benefit of the EU’s vehicle CO2 regulations, the report says. Additionally, it can result in a competitive disadvantage for automakers whose actual CO2 emissions more closely align with their reported emissions, and can lead to consumer distrust.
Earlier this month, BMW chairman Norbert Reithofer called the EU’s strict vehicle emissions standards “impossible to meet.” He said the targets can’t be met without huge investments — requiring government support — in expensive alternative drivetrain technology.