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Euro Norms: The technicalities, backlash & watered down Euro-7!

13th July 2024, 16:22 by Ananth Iyer

The aim of these emission norms was to set a standard of emissions a vehicle should adhere to, for a greener and cleaner environment.

BHPian saket77 recently shared this with other enthusiasts.

What were the Euro Norms and why the need?

I believe the opening picture explains quite a bit of 'why the need' part of the question.

The Euro emission norms were introduced in the Europe in Jul 1992. The aim of these emission norms was to set a standard of emissions a vehicle should adhere to, for a greener and cleaner environment. These series of regulations, which are designed to become more & more stringent over time, define acceptable limits for exhaust emissions. The climate change due to pollution and its ill-effects on general populace & the flora is a vast topic in itself which needs separate discussion. Hence, I am purposefully avoiding going that route so as to not deviate from the technicalities of the subject. But surely, we had to contain the automobile pollution coming off from the tailpipes of ever increasing car numbers for our own good.

Euro-I

The first such attempt in the Euro series to taper the exhaust gases was called Euro-I standard and was applicable to all land surface vehicles sold in European Union from 1992. Also, the water vessels in EU waters were needed to comply. One important point to note was that all new vehicles being sold in the EU had to comply with these Euro norms, but the existing ones already plying on the roads, which largely were non-compliant, were exempt and could be driven around freely.

The main pollutants identified to be tapered were the Nitrogen Oxides (NOx), Hydrocarbons (HC), Carbon Monoxide (CO) and particulate matter (PM). The diesel engines have a notorious reputation for spewing particulate matter. Now, since the petrol and diesel engines emissions are different, separate norms were setup for both.

Euro 1 emission limits

CO – 2.72 g/km (petrol and diesel)
HC+ NOx – 0.97 g/km (petrol and diesel)
PM – 0.14 g/km (diesel only)

To achieve these end results, a double-sided 'in-out' approach was needed. A switch to unleaded fuel was required from the side of oil refiners (in-side) and fitment of catalytic converters was required from the automaker’s side (out- side).

Tetraethyl lead, since 1920s was used as a cheap way to boost the octane rating of fuel. Contrary to popular belief, octane is not an indicator of the amount of energy in gasoline, but instead the temperature at which the fuel ignites. Engines running at higher compression ratios (& hence higher temperatures inside the cylinder) would have been prone to knocking if the octane number wasn’t ‘boosted’ by using lead in gasoline, since plain gasoline would ignite before the spark plug actually fired due to the already high temperature in the cylinder. Also, lead allowed for better valve lubrication and hence longer engine life. So, lead in fuel was used as an ‘anti-knock’ agent with lubrication properties and these could run in higher compression engines without detonating prematurely.

The downside- burning of leaded gasoline increases the concentration of lead in the air to a measurable level in the blood of humans. High levels of inhalation of such gases may cause neurological damage, anemia, brain damage, convulsions and even death to humans.

On the automaker’s side, fitment of catalytic converter was required as a ‘treatment’ for the exhaust fumes after combustion. These catcons had metal elements inside (including expensive ones like platinum, rhodium and titanium) which reacted with exhaust gases to break & filter them into different compounds to reduce obnoxious and poisonous components spewed by cars.

So, in a nutshell, lead had to go from fuel and catalytic converters had to be fitted to all cars. Euro-I emission standards were thus achieved.

Maruti Suzuki in India marked their E-1/ BS-I compliant cars as 'Greenwheels' in around 1999.

Euro-II

5 years down the line and Euro-II norms kicked off. The new norms were much stricter than Euro-I. This meant that carburetors had to go out and Multi-Point Fuel Injection technology made to mainstream cars. The MPFI technology made liberal use of sensors fitted in different areas and stages of combustion to monitor different parameters in real-time and adjust car’s intake of fuel-air mix to achieve the most efficient ratio. This vast change in the technology for regular cars saw not only meeting them to Euro-II standards but also big gains were made in the area of performance and fuel efficiency. The availability of MPFI tech to general consumers can be said to be a big turning point in automobile performance, efficiency, reliability and maintenance. This E-1 & E-II period also saw India witnessing coming of global players like Hyundai, Daewoo, etc with their products like the Santro, Matiz, etc which dotted the new-generation 2K cars of India. Maruti-Suzuki, the market leader also jumped into the war-scene fully armed with some superior engine technologies & specs w.r.t. some competitors.

However, the advent of E-II also saw demise of many engines and even manufacturers being wiped off from the Indian auto scene who could not keep up with the technology or financial viability of this upgrade.

Notice the same engines with carburetor and the modern E-II compliant MPFI tech:

Euro 2 emission limits (petrol)

CO – 2.2 g/km
HC+ NOx – 0.5 g/km
PM – no limit

Euro 2 emission limits (diesel)

CO – 1.0 g/km
HC+ NOx – 0.7 g/km
PM – 0.08 g/km

The PM limit for petrol cars were not set in Euro-II as petrol vehicles hardly emitted noticeable particulate matter (until the introduction of gasoline direct injection / GDI engines later). It was the diesel engines for which PM was an issue and hence a cap was set in E-II norms.

Euro 3, 4 & 5

Euro 3 modified the test procedure to eliminate the engine warm-up period to achieve full efficiency sooner and further reduced permitted carbon monoxide and diesel particulate limits. Euro 3 also added a separate NOx limit for diesel engines and introduced separate HC and NOx limits for petrol engines.

Euro 3 emission limits (petrol)

CO – 2.3 g/km
HC – 0.20 g/km
NOx - 0.15
PM – no limit

Euro 3 emission limits (diesel)

CO – 0.64 g/km
HC+ NOx – 0.56 g/km
NOx – 0.50 g/km
PM – 0.05 g/km

Euro 4 and the later Euro 5 concentrated on cleaning up emissions from diesel cars, especially reducing particulate matter (PM) and oxides of nitrogen (NOx).

Some Euro 4 diesel cars were fitted with particulate filters.

Euro 4 emission limits (petrol)

CO – 1.0 g/km
HC – 0.10 g/km
NOx – 0.08
PM – no limit

Euro 4 emission limits (diesel)

CO – 0.50 g/km
HC+ NOx – 0.30 g/km
NOx – 0.25 g/km
PM – 0.025 g/km

Euro 5 further tightened the limits on particulate emissions from diesel engines and all diesel cars needed particulate filters to meet the new requirements.

There was some tightening of NOx limits too (28% reduction compared to Euro 4) as well as, for the first time, a particulates limit was set up for petrol engines – applicable to direct injection engines only. This became a necessity because many automakers started selling direct injection gasoline engines like for eg. TSI engine of VW.

Addressing the effects of very fine particle emissions, Euro 5 introduced a limit on particle numbers for diesel engines in addition to the particle weight limit. India skipped the E-5 norms to catch up with Europe and adopted E-6 straightaway.

Euro 5 emission limits (petrol)