Two-tonne diesel beats all petrol cars and matches full hybrids in eco tests

Modern diesel cars can be surprisingly low on emissions, Green NCAP’s results show. The Mercedes-Benz E-Class is less polluting than all petrol cars the environmental body has tested so far – and even gives many hybrid cars a run for their money. We reveal the full results below.

Below, we reveal how the result for the Mercedes-Benz E-Class diesel mild hybrid compares to other cars tested by Green NCAP.

 – our complete lab and road tests ensure you don’t get caught out.

Two-tonne diesel beats all petrol cars and matches full hybrids

In what Green NCAP calls a ‘truly astonishing achievement’, its tests on the diesel Mercedes-Benz E-Class give it an overall score of three stars out of five, and it lauds the diesel mild hybrid as the ‘cleanest combustion-engine vehicle Green NCAP has tested so far’.

Its score beats large numbers of petrol cars, such as the Kia Sportage (two stars out of five) and Peugeot 308 (two stars), and even beats four petrol mild hybrids (all of which were tested by Green NCAP in 2022-2023):

Nissan QashqaiFord FiestaFord FocusMercedes-Benz C-class

In addition, the E-Class exceeds the Hyundai Tucson full hybrid, which scored only 2.5 stars due to high particulate ( the total number of solid particles emitted from the vehicle exhaust) and ammonia emissions, plus mediocre carbon dioxide emissions. Unlike mild hybrids, which have a small battery that helps lower fuel use, full hybrids have a much larger battery and, consequently, score higher Green NCAP tests.

The Mercedes-Benz E-Class’ result of three stars out of five matches a slew of full hybrid cars in Green NCAP’s current 2022-2023 tests, including:

Dacia JoggerFiat 500 hybridHonda HR-V hybridRenault Austral hybridToyota Yaris Cross hybrid

Below, you’ll find all the results from the independent body’s newest tests, including the electric cars that came out on top.

Mercedes-Benz E-Class (diesel mild hybrid, £55,290**)

Green NCAP score: 3/5

Green NCAP tested the two-litre diesel version of the E-Class, which has a 48V mild-hybrid system. It’s a luxurious vehicle, itself weighing 2,077 kg – and despite this, delivers unexpected results.

It achieves an incredible score of 9.3 out of 10 in the Clean Air Index test, which looks for air pollutants like NOx, carbon monoxide and particulates that can collect in health-harming levels in cities – and have traditionally given diesel cars a bad name. 

Not so here. Green NCAP rates every gas in its Clean Air test to be at ‘good’ or ‘adequate’ levels, regardless of whether the car is starting cold or warm, on the motorway or on a short trip. This is the best result a combustion-engine car has ever achieved in this assessment, including any petrol car.

Green NCAP praises the car in particular for minimising NOx emissions to ‘practically non-existent’ levels, while particulates are rated as ‘good’ or ‘adequate’ in all tests.

Unfortunately it’s not a complete thumbs up from Green NCAP for the E-Class. It only scores 1.9 out of 10 in the Greenhouse Gas test on the car’s contribution to climate change. The car is good at controlling methane emissions, but carbon dioxide emissions are overall rated as weak (you'd usually expect a diesel to be better for carbon dioxide emissions than a petrol car, but that isn't the case here). In addition – as is typical for all diesel cars – N20 emissions are poor. These results are also pulled down as Green NCAP takes into account emissions related to the production and supply of the diesel fuel, not just the running of the vehicle

Green NCAP technical manager Dr Aleksandar Damyanov said: ‘The strong results clearly demonstrate the achievements made in the quest for cleaner and less climate damaging cars, including those powered with conventional engines.’

We haven't yet lab tested the new Mercedes-Benz E-Class, but you can see if the previous generation of the E-Class is worth buying used in our .

Dacia Jogger (petrol full hybrid, £18,295*)

Green NCAP score: 3/5

Green NCAP tested the 1.6-litre petrol full hybrid Dacia Jogger, and you might have hoped for a better score when buying a hybrid.

It performs averagely in all three of Green NCAP’s test areas, scoring 5.6 out of 10 in the Clean Air tests, 5.5 for Energy Efficiency and 4.2 for greenhouse gas emissions.

In the Clean Air tests, release of particulate matter particularly is rated as weak, and in the Greenhouse Gas test, carbon dioxide emissions are rated weak during motorway driving and in the cold lab test.

Is this keenly-priced car a strong overall package for the price? Our experts give their verdict in our .

Skoda Kamiq (petrol, £21,441*)

Green NCAP score: 3/5

With its one-litre turbocharged petrol engine, Green NCAP gives the Skoda Kamiq small SUV the same overall score as the Mercedes-Benz E-Class – the Kamiq performs better in the Greenhouse Gas test, but can’t quite match the heights of the E-Class in the air pollution tests.

It scores 7 out of 10 in the Clean Air tests, 5.2 for Energy Efficiency and 3.8 for greenhouse gas emissions, where carbon dioxide emissions are rated weak on the motorway and in the cold lab test.

Could this be the perfect car for you? We comprehensively test this car leaving no stone unturned – find out the full results in our .

Audi A6 (diesel mild hybrid, £44,650**)

Green NCAP score: 2/5

Green NCAP tested the Audi A6 with its three-litre turbocharged diesel engine, and its result of two stars out of five shows you do have to choose your new diesel mild hybrid car carefully.

That said, Green NCAP points out the A6’s ‘diesel mild hybrid powertrain is more efficient than its petrol counterpart’, and that it depends on the A6 you choose, stating ‘its lighter and less powerful variants might perform better in Green NCAP’s tests.’

The Audi A6 it tested scored 6.9 out of 10 in its Clean Air tests, 3.4 for Energy Efficiency (which Green NCAP says is ‘creditable’ considering this is a two-tonne car with a big engine) and 0.8 in the Greenhouse Gas tests.

Carbon dioxide emissions are rated weak in Green NCAP’s cold and warm tests for greenhouse gases, and rated poor on the motorway, while it found N2O emissions are always rated poor (which is usual for diesel cars).

We haven’t tested this latest version of the Audi A6, but see if it’s worth buying used with our .

Ford Ranger (petrol, £28,275*)

Green NCAP score: 1/5

With a three-litre, twin-turbo V6 petrol engine, we doubt many buy the Ford Ranger with environmental footprint at the top of their priority list.

The Ford Ranger pick-up truck is approved for sale as a commercial vehicle (so it doesn’t have to meet the same stringent legislative requirements as regular passenger cars), but has also found a niche as a family ‘utility’ vehicle.

It fails to score any points at all for Energy Efficiency or greenhouse gas emissions, with a rating of 0 out of 10, with a weak score of 3.5 in the Clean Air test, where ammonia emissions are particularly poor.

The car’s high fuel consumption means it has poor carbon dioxide emissions in the greenhouse gas assessment – with the results completely off the charts compared to what you’d expect from regular passenger cars.

We haven't reviewed the Ford Ranger, but you can read our  to see all we've tested, including a few 'muscle' cars.

Ora Funky Cat (electric, £31,995*)

Green NCAP score: 5/5

Green NCAP’s tests now factor in the environmental impact from the production of electricity, which is a key consideration for electric cars. Even taking this into account, given the reasonable level of electricity generated by renewables these days, the environmental impact of electric cars is much lower than any combustion-engined car.

The Ora Funky Cat compact family car unsurprisingly scores 10 out of 10 in the Clean Air test (given it has no tailpipe emissions), 9.5 in the Energy Efficiency assessment, and 9.8 for release of greenhouse gases.

There are plenty of Chinese-brand electric cars releasing these days, but are they any good? We give our independent impressions in our First Drive .

BYD Atto 3 (electric car, £37,695*)

Green NCAP score: 5/5

BYD may not be a UK household name, but the Chinese brand was the best-selling brand worldwide for electric and plug-in hybrid vehicles last year – so it’s certainly a brand to watch.

Its Atto 3 compact SUV gets a near-flawless clean sweep in Green NCAP’s tests, scoring 10 out of 10 in the Clean Air test. 9.5 for Energy Efficiency and 9.7 for greenhouse gas emissions.

It particularly stood out in Green NCAP’s tests for the car's low energy usage in cold weather conditions, thanks to its well-designed heating system which uses a heat-pump and a range of different sources of waste heat to provide the right level of warmth in the cabin.

Is this the electric car you’ve been waiting for? Check out our full .Looking for more options? See all our .*New prices based on what people pay (including discounts), sourced from 500 franchised dealers across the UK each month.**For cars we haven’t reviewed yet, these are the On-The-Road prices from the manufacturer’s website, correct at time of publishing.

source https://www.which.co.uk/news/article/two-tonne-diesel-beats-all-petrol-cars-matches-full-hybrids-in-eco-tests-axu4H2r6qhys