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Jamie Gibbs

The worst cars for emissions and their greener alternatives


In the aftermath of the Volkswagen scandal, cars’ emissions are still in the spotlight.

Worst cars for emissions

In September 2015, it was uncovered that Volkswagen was rigging emissions test results, allowing hundreds of thousands of diesel vehicles to go under the radar of strict nitrogen oxides (NOx) tests.

Since then, many automakers have been under investigation and, according to data from Which?, the rabbit hole is deeper than previously thought.

What are the emission standards?

The European exhaust emissions standards date back to the early 1970s. Since then, they’ve been reviewed six times, gradually introducing tighter limits to reduce the negative impact these emissions are having on the environment.

The first standard introduced is known as Euro 1, and the latest revision (introduced in 2015) is Euro 6.

Every car sold and driven in Europe has to meet standards for carbon dioxide (CO2), carbon monoxide (CO), nitrogen oxides (NOx), hydrocarbons (HC) and particulate matter (PM).

Euro 6 is the latest iteration and it applies to all new cars registered after September 2015. However, cars registered between 2011 and 2014 need to abide by the limits of the Euro 5 standard.

Although NOx emissions don't have any monetary impact on drivers, it's something to keep in mind. The selection of the more eco-friendly cars is based on official data.

The five worst diesel powered offenders on the road

Euro 5’s NOx emissions limit is 0.18g/km, and for Euro 6 cars that’s 0.08g/km.

Worst petrol cars

Here are the five worst diesel cars:

1. Jeep Grand Cherokee, 3.0-litre (2011 on) - emits 2.7 g/km of NOx.
Alternative – BMW X5 sDrive25d – 0.041 g/km of NOx

2. Subaru Forester, 2.0-litre (2013 on) - emits 1.19 g/km of NOx
Alternative – Toyota RAV4 D-4D – 0.025 g/km of NOx

3. Nissan X-Trail, 1.6-litre (2014 on) - emits 1.05 g/km of NOx
Alternative – Ford Kuga TDCi Zetec- 0.058 g/km of NOx

4. Nissan Qashqai, 1.6-litre (2014 on) - emits 0.99 g/km of NOx
Alternative – Vauxhall Mokka CDTi – 0.048 g/km of NOx

5. Kia Sportage, 2.0-litre (2010 on) - emits 0.93 g/km of NOx
Alternative – Mazda CX-5 SE-L – 0.068 g/km of NOx

The five worst petrol powered offenders on the road

Diesel cars weren’t the only ones Which? found to defy the NOx emission limits.

Worst diesel cars

These five petrol cars’ emissions are over the Euro 5 and Euro 6 0.06g/km limit:

1. Mercedes-Benz SL, 3.5-litre (2012 on) - emits 0.2 g/km of NOx
Alternative – BMW Z4 sDrive18i - 0.024 g/km of NOx

2. Mercedes-Benz E-Class, 2.0-litre (2009 on) - emits 0.17 g/km of NOx
Alternative – BMW 5 series TFSI – 0.032 g/km of NOx

3. Mini Cooper, 1.5-litre (2014 on) - emits 0.16 g/km of NOx
Alternative - Fiat 500 – 0.013 g/km of NOx

4. Nissan Pulsar, 1.2-litre (2014 on) - emits 0.15 g/km of NOx
Alternative – Hyundai i30 – 0.008 g/km of NOx

5. Nissan Qashqai, 1.2-litre (2014 on) - emits 0.12 g/km of NOx
Alternative – Renault Kadjar TCe – 0.015 g/km of NOx


Data on NOx emissions of the alternative cars has been taken from official data published on
The full research conducted by Which? can be found here.


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