Table 6 Performance and score of Euro norms

Target achievement

 (1)

Significant reduction of CO, NO_x, SO_x, C_nH_m, PM, and PN (see SM2)

Several studies show a connection between early statistical deaths and harmful vehicle emissions

Significantly fewer air pollution-related diseases in hospitals were found before the introduction of LEZ in 2012 due to better emissions standards

Supported new low-emission technologies market entry, which leads to a reduction of emissions

[71]

[13]

[58]

 (2)

EU-wide standard categories for newly registered vehicles (cars, LDV and HDV), independent of their gross vehicle weight

Standards are revised and renewed due to the availability of technologies with lower emissions

The base unit for cars and LDV is kilometers, while it is ton-kilometers for HDV

[30]

 (3)

Indirect reduction of CO₂, because decreasing consumption was crucial for harmful emissions mitigation (downsizing, turbocharger)

CO₂ value according to WLTP decisive for vehicle taxation

[41]

 (4)

Testing standards for Europe (new European driving cycle—NEDC) and since 2017 worldwide harmonized light vehicles test procedure (WLTP) for cars

Vehicles are optimized for the test cycle, not representing real driving emissions

The introduction of WLTP and testing real-driving emissions (in-service testing) made a conformity factor necessary

[18]

[21]

[21]

Cost-efficiency

 Estimated avoided damage cost: 8,611 Mil. € (damage cost functions) for a reduction in NO_x for EU28 over the period 2009–2013

[15, 22]

 A cost increase of mandatory reduction technologies of 1% for gasoline and 5–6% for diesel LDV (regarding average car price of 30,000 $ in 2012)

[42]

Practical feasibility

 Cold start emissions were not considered until 2021

 Real-world emissions are not represented in driving cycles—in-service emissions since Euro VI

 The onset of effect: Euro IV took seven years (2014–2021) to reach a fleet share of 40% (see Additional file 1: SM 7)

[18]

[21]