Plug-in hybrid beaten by latest diesel cars in eco tests
It’s a mistake to assume plug-in hybrid cars are always a better choice than traditional combustion-engine cars for lower air pollution, Green NCAP’s tests show. The Mazda CX-60 plug-in hybrid is the latest hybrid to fail to beat the best diesel cars in the environmental body’s professional tests. Find out all the results below.
Green NCAP’s latest results once again highlight the dramatic variation in the environmental impact of hybrid models, and how the latest emissions control tech means diesels sometimes outperform hybrids.
Find out how the Mazda CX-60 compares to other hybrid and diesel cars recently tested by Green NCAP.
Best cars for 2023 – our car recommendations cover all bases so you can ensure you’re getting a car that’s great for your wallet and low on emissions
Plug-in hybrid fails to beat latest diesels
The Mazda CX-60 is Mazda’s first vehicle available as a plug-in hybrid, and it’s this version Green NCAP has tested – it's also the one you’d hope would have the least environmental impact.
But Green NCAP’s assessments give it an overall score of only two and a half stars out of five. The organisation warns: ‘The label of ‘hybrid’ does not automatically mean it outperforms a well-managed combustion-engine vehicle.’
It’s beaten by the latest diesel cars in Green NCAP’s tests. These include the two-tonne Mercedes-Benz E-Class (three stars out of five, £55,290**) we reported on in September – which even beat all petrol cars on raw scores in its tests – and the performance-oriented BMW 2 Series Coupé (also three stars, 35,889**). Both the Mercedes and the BMW are diesel mild hybrids.
It’s not just premium-priced diesels either. Green NCAP tested the diesel version of the Vauxhall Mokka and gave it three stars out of five (though this diesel version isn't currently on sale in the UK).
Green NCAP technical manager Aleksandar Damyanov says: ‘More power does not necessarily result in more impact on the environment. Our independent consumer information shows consumers need to pay attention to ensure their cars are as green as they claim to be, and not assume hybrids make a greener powertrain.’
Below we reveal all the results from Green NCAP’s most recent test, including the electric cars that came out on top.
Mazda CX-60 (petrol plug-in hybrid, £43,337*)
Green NCAP score: 2.5/5
Mazda’s first plug-in hybrid is a large and luxuriously fitted SUV, offering plenty of power and torque – but that’s no excuse for the disappointing results when hefty diesels have outperformed it.
In Green NCAP’s Clean Air tests, the car scored only 5.4 out of 10. Weak particulate emissions in the cold and motorway tests are particularly surprising as this is a problem most common on older diesel cars.
Ammonia and carbon monoxide emissions are also weak when the engine is starting from cold, and Green NCAP found they got even worse on the motorway, rating the levels of these emissions as poor.
In Green NCAP’s other assessment areas, the CX-60 received an awful 4.1 out of 10 in its greenhouse gas tests, with high carbon dioxide emissions to blame, and a disappointing 5.0 out of 10 in the energy efficiency test.
Green NCAP warns the car's claimed electric range of 39 miles (63km) didn’t stack up in its tests (which simulate the conditions you’d expect when actually driving in the vehicle), saying it only achieved 32 miles (51km) of electric-only driving. This means that the car’s petrol engine has to kick in much earlier, leading to weaker fuel economy, particularly on the motorway.
This is only part of the story – see if this might be a car that excels in other areas in our comprehensive Mazda CX-60 plug-in hybrid review.
Mazda’s also taken the bold step this year of adding a diesel version with a big 3.3-litre six-cylinder engine – for this, see our Mazda CX-60 mild hybrid review.
Alfa Romeo Tonale (petrol mild hybrid, £37,634*)
Green NCAP score: 2.5/5
This strikingly styled SUV gets the same mediocre star rating as the Mazda CX-60 in Green NCAP’s tests. It’s not quite as disappointing though given it’s only a mild hybrid (meaning it only has a small 48V battery supporting the petrol engine), rather than a plug-in hybrid.
That said, this result has still been beaten by the large Mercedes and performance BMW diesel mild hybrids mentioned above, as well as the following purely combustion-engine cars tested by Green NCAP in 2022-23 (although the following cars are to varying degrees smaller), showing what can still be done with no hybrid technology whatsoever:
- VW T-Roc (petrol, three stars out of five)
- Vauxhall Mokka (diesel, three stars)
- Skoda Fabia (petrol, three stars)
- Skoda Kamiq (petrol, three stars)
- Kia Picanto (petrol, three stars)
- Toyota Aygo X (petrol, three stars)
In Green NCAP’s assessments, the Alfa Romeo Tonale with its 1.5-litre turbocharged petrol engine narrowly beats the Mazda CX-60 in the clean air tests (5.5 out of 10), but performs worse in the energy efficiency test (4.4 out of 10) and particularly poorly for its greenhouse gas emissions (2.7 out of 10).
Green NCAP shows its carbon monoxide emissions are particularly poor for motorway driving, although they’re also weak when the engine starts from cold.
For air pollution, ammonia emissions are the most glaring issue – Green NCAP gives it its worst rating of ‘poor’ in all its tests, whether the engine’s starting from cold or warm, or on the motorway. Carbon monoxide emissions are also weak with a cold-start engine and poor on the motorway.
Fuel economy suffers in motorway driving too, where Green NCAP says the mild hybrid system is ‘not able to assist enough’ during fast acceleration and high speeds; its SUV body design also heightens aerodynamic drag.
Could this be a great car to choose for other reasons? Find out what our professional testers thought out on the road in our Alfa Romeo Tonale first-drive review.
Best electric cars for 2023: discover which EVs aced our lab tests
Tesla Model S (electric, £93,480*)
Green NCAP score: 5/5
Tesla’s flagship Model S is a great example of how a performance car with innovative technology can be an environmentally conscious choice too, according to Green NCAP’s tests.
It completely blitzed the standard assessments, scoring 97% overall, with 9.7 out of 10 for greenhouse gas emissions, 9.4 out of 10 for energy efficiency and, of course, 10 out of 10 for air pollution given it doesn’t have a tailpipe.
Green NCAP tested the Dual Motor version, offering plenty of torque. It says: ‘The Model S sets an example for pure electric luxury cars, with an uncompromised focus on driving range, efficiency and thermal comfort (efficiently heating the cabin) despite an abundance of power.’
Get the full picture in our definitive Tesla Model S review.
MG 5 (electric, £30,285*)
The MG 5 goes one step further than most electric cars in the assessments. Green NCAP also conducts a life-cycle analysis of each car it tests, which takes into account the energy required to produce the electricity (the European average), and it’s only the fifth car Green NCAP have tested so far to earn its ‘Greener Choice’ award.
It gets a near clean-sweep in Green NCAP’s standard assessments, with 9.5 out of 10 in the greenhouse gas tests (this takes into account the emissions from the electricity generation), 9.2 out of 10 in the energy efficiency tests, and 10 out of 10 for Clean Air, given it has no tailpipe emissions.
Green NCAP said the energy efficiency rating particularly ‘impressed’, as it means very little electricity is wasted, saving costs to the owner.
Find out if this car excels just as much across the board, or if there is anything you should watch out for, in our full MG 5 review.
Renault Kangoo (electric, £22,225**)
Green NCAP score: 5/5
It’s not just cars that contribute to air pollution and environmental impact of course, so Green NCAP has for the first time tested an electric van, to see if it stacks up to electric cars.
While it does achieve a full five stars out of five from Green NCAP, it was nail-bitingly close (it scored 90% overall). The Kangoo only scored 8.5 out of 10 in the Energy Efficiency test, with only adequate scores on the motorway (it’s mainly designed for short urban trips). This this was also the case in the cold conditions test. Performed at -7°C, Green NCAP found twice the energy is used compared the standard test.
The Kangoo scored 8.7 out of 10 in the greenhouse gas tests (the lower energy efficiency on the motorway and cold conditions mean more electricity generation emissions), and 10 out of 10 for local air pollution (Clean Air), since it's an electric vehicle.
Green NCAP also discovered the efficiency of charging and discharging the car is ‘rather poor’ (by electric car standards): only 84% of the electricity withdrawn from the electricity grid actually makes it to driving the car.
We haven’t reviewed the latest Renault Kangoo yet, but to find all 1,000+ cars on the market we’ve tested, see our new and used car reviews.
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**For cars we haven’t reviewed yet, these are the on-the-road prices from the manufacturer’s website, correct at time of publishing.
