The first legislation for road vehicles was issued as early as 1970 when the principle of type approval (70/156/EEC) and the first Emission Measures for motor vehicles (70/220/EEC) were established. These Directives are the basis for the requirements for light vehicles (passenger cars and commercial vehicles below 3.5 tonnes) known as Euro 1-6 and those for heavy duty vehicles (trucks and buses) known as Euro I-VI. Both represent a series of increased tighter emission requirements and include detailed instructions on the methods and conditions to establish them.
The legislation addresses type approval of new models. Producers should know in advance the requirements for their new models, in order to comply with legislation when they introduce them on the market. As a result there is a time gap between the date that the legislation is approved and the date when it comes into force. This time gap may vary considerably (2-7 years).
The type approval procedure focuses on the results of emission measurements of the respective vehicle. For light vehicles these are made while the car follows a standard test cycle while running on a dynamometer. The test cycle, which is designed to reflect real traffic conditions, has been modified a few times. For heavy duty vehicles only the engine is tested under standardized conditions. On-road measurements, however, show considerable discrepancies from the type approval data.
Emission reductions during the seventies and eighties originated from maintenance requirements and minor modifications of the engine; with the exception of carbon monoxide they were not substantial. In addition, during that period emissions of sulphur dioxide (diesel) and lead (petrol) were reduced by fuel quality requirements. Major progress was achieved by the introduction of the 3-way catalyst exhaust treatment with Euro 1 (petrol). For diesel engines subsequent improvements in the technology were sufficient to comply with Euro 4, presently in force (98/70/EC). The requirements of Euro 5 and 6 force industry to introduce catalytic converters for NOx and filters for PM. Publication of a respective Directive will follow after technical details have been defined. The developments are reflected in Table 1.
Table 1. Development of emission requirements for light vehicles
|PM (mg/km)||NOx (g/km)||HC (g/km)||HC + NOx (g/km)|
|Euro 1 (1992-93)||140||–||–||–||–||–||0.97||0.97|
|Euro 2 (1996)||80/1001)||–||–||–||–||–||0.7/0.91)||0.5|
|Euro 3 (2000)||50||–||0.50||0.15||–||0.20||0.56||–|
|Euro 4 (2005)||25||–||0.25||0.08||–||0.10||0.30||–|
1) For Indirect injection and Direct injection engines respectively
2) For lean burn direct injection vehicles