When it comes to the control of greenhouse gas emissions, it is the EU that has stricter
standards (in addition to generally higher fuel taxes in EU Member States than in the US).
Table 1 below shows a comparison of emissions standards for pollutants in the US (Tier 3)
and EU (Euro 6). It should be stressed that the US pursued technically-neutral standards
between petrol and diesel cars, unlike the EU which allowed looser standards in NOx and
particulates for diesels.
Table 1: Comparison of emission standards for pollutants in the US and EU4
Emissions standards for pollutants (g/km) US EU
Nitrogen oxides (NOx) 0.04 0.06/0.08*
Non-methane organic gases (NMOG) 0.06 0.07/na*
Carbon monoxide (CO) 2.61 1.0/0.5*
Carbon Dioxide (CO2, in 2016) 155 130
Carbon Dioxide (CO2, in 2020) 132 95
Form of vehicle emission testing FTP NEDC
*Petrol / diesel standards
Federal Test Procedure (FTP)
New European Driving Cycle (NEDC)
Sources: DieselNet5 and Delphi (2015)6
As shown in Table 1, EU standards differ for petrol as compared to diesel; in the US the same
standards apply to both. Historically, diesel cars have played a marginal role in the US market
while in approximately half of all cars in the EU sold are diesel cars7. This different standards
for diesel in the EU reflects a combination of the greater technical challenge in reducing these
emissions in diesel vehicles, and a European and Member State policy priority in favour of
diesel in the 1980s and beyond, in view of its potential for reducing CO2 emissions. This was
also reflected in lower diesel taxes, which, in combination with the relative fuel efficiency and
hence cost-effectiveness of diesel cars are among the reasons for their high market
penetration in the EU.