Eco-friendly cars

Low emissions, excellent fuel economy and lots of electric options: these are the most environmentally-friendly cars available

Craig Hale
Oct 13, 2021

Buying an environmentally-friendly car is quite easy these days, as most cars are subject to strict emissions regulations that make them an awful lot cleaner than the same car would’ve been 10 or 15 years ago. That doesn't mean you have to buy an electric vehicle for your next car - although they are undoubtedly some of the cleanest options (and come with tax benefits). There are dozens of petrol- and diesel-powered models that can rightly claim to be eco-friendly, certainly by the standards of most cars.

These vehicles offer excellent fuel economy, which is good news for your wallet, as well as ensuring reduced emissions of the greenhouse gas carbon dioxide. They also release low levels of toxic nitrogen oxides (NOx) and tiny soot fragments called particulates, which have been linked to early deaths.

Many of the cleanest cars are hybrid vehicles. As well as a petrol or diesel engine, these have batteries and a motor, which can recover energy that's usually lost during braking and use it to power the car. Some hybrids are plug-in models, with larger batteries that can be charged to provide around 20-40 miles of electric driving before the engine is needed.

The introduction of new, tougher emission tests means that the latest cars are now tested on the road as well as in the laboratory to ensure that they remain clean in real-world driving. That means cars tested under the old ‘NEDC’ system should have their emissions figures taken with a heavy pinch of salt; newer cars tested under the latest ‘WLTP’ system may have a lower figure on paper but may well be more efficient in real life as they benefit from the latest technology and efficiency measures. But it's still possible to find a green car that's affordable, as you'll see below.

We've used the latest data from the government's Vehicle Certification Agency, which lists official emissions and fuel economy results for new cars.

Click below to find the most environmentally-friendly cars in each category, or scroll down to see the full list - as well as advice on buying an environmentally-friendly car.

Most environmentally-friendly cars by category

How to buy an environmentally-friendly car

Is it more environmentally friendly to keep an old car or buy a new one?

It's often argued that running a car into the ground is the most environmentally considerate option, given the quantity of carbon dioxide emitted during production. A 2011 study funded by the Government and transport industry found that a typical family car with a conventional engine will create the equivalent of 24 tons of carbon dioxide by the time it is scrapped, and 5.6 tons are from production.

However, this doesn't take into account the large fuel economy and emissions improvements made by the very latest models. Neither does it account for the higher level of harmful emissions produced by many older cars, which are pumped out into towns and cities. This is one of the main arguments for buying a cleaner new car, as you are helping to improve the air quality for the local area - and the cumulative effect of many people buying eco-friendly cars would lower pollution on a wider scale.

Some manufacturers offset the carbon produced during the manufacturing process - Volkswagen claims to build its ID.3 carbon-neutral. While this is a good effort, not producing the carbon in the first place is the best option, which is down to us as consumers to limit our demand for brand-new cars.

Are smaller engines more environmentally friendly?

Not always. Small engines can feel quite weedy if they’re not fitted with a turbocharger, so you may find yourself having to rev hard to make good progress. If this is the case, your fuel consumption and emissions output will both be high. Turbochargers, which force more air into an engine's cylinders, increase power without using much more fuel. However, the heat from this process tends to produce higher levels of toxic nitrogen oxides. As a result, some manufacturers, such as Renault and Nissan are starting to produce larger engines, which don’t need working as hard. It's telling that the cleanest diesel engines below, which have passed the very latest emissions tests, are all at least 1.5-litres in size.

Environmentally-friendly electric cars

Electric cars seem to be the solution, at least for now, but they too must get their energy from somewhere. While many suppliers are promising green electricity, it still makes sense to buy a car that uses electricity as efficiently as possible, maximising the number of miles from each unit of power (kWh).

As well as reducing demand on power stations, efficient power use will increase the range of the car and allow manufacturers to use fewer batteries, which cuts cost and weight.

You can read our guide to the most economical electric cars to make sure you're getting as many miles as possible per kWh of electricity.

1. Fiat 500

Economy 4.8 miles per kWh
Used deals Limited stock

While Fiat continues to sell mild hybrid versions of the outgoing 500, this redesigned model is limited to electric power only. The less powerful entry-level model comes with a smaller battery, capable of a claimed 115 miles, while the more powerful models also get a larger battery, allowing the city car to travel up to 199 miles (Fiat claims over 280 miles for urban-only driving). Both models support rapid charging for an 80% battery top-up in around 30-35 minutes - 50kW charging for the entry-level model and 85kW for the others. Regardless of the version, the Fiat 500 should be able to achieve well over 4 miles per kWh when driven in its natural environment - the town.


2. Hyundai Ioniq

Hyundai Ioniq Electric front three quarters view

Economy 4.5 miles per kWh
Used deals from £17,990
Monthly finance from £0*

It's the latest version of the Ioniq that promises a high efficiency figure; the Ioniq Electric's 38kWh battery means it can travel for almost 200 miles, although we would hedge our bets closer to 150 miles in the real world. Earlier models are more likely to travel for between 100-150 miles in the real world, but 50kW DC charging will help top up 80% of the battery's capacity in around an hour. Unlike many electrified models, the Ioniq was built with the environment at its core; three versions exist: a self-charging hybrid model, a plug-in hybrid model, and this electric model. 


3. Hyundai Kona

Economy 4.3 miles per kWh
Used deals Limited stock

To buy new, this Kona is about £2,500 cheaper than the Ioniq, with which it shares many of its electrified parts and comes in a trendy crossover body style. It does have one clear benefit, though: the option of a larger 64kWh battery which promises a range of 300 miles. It's not slow, either - in its most powerful form, it produces over 200hp. Use all of this all the time, though, and you're likely to see an impact on battery life. Fortunately, the Kona comes with 100kW rapid charging, so 10% to 80% should take just over 45 minutes. Remember, 80% of this car's battery is different to 80% of another car's battery, so it's not as simple as just comparing the time it takes. 


4. Renault Zoe

Economy 4.0 miles per kWh
Used deals from £8,000
Monthly finance from £346*

The Zoe was one of the first mainstream electric cars, and as such, there are plenty of used examples on BuyaCar. Early models were rather cheap - around £15,000 when new - but with electric cars in their infancy, they are barely able to manage 100 miles on a full charge. Fine if you don't travel long distances, but if you prefer to venture further afield, a newer version should appeal, with a range of up to 245 miles thanks to a 52kWh battery. Renault has also removed the option to lease the battery, which made the Zoe cheap on paper but required an extra monthly payment of around £100.


5. Smart ForTwo

Economy 4.0 miles per kWh
Used deals from £17,991
Monthly finance from £0*

Whether you go for this, the soft-top ForTwo Cabrio, or the roomier ForFour, don't expect high-end figures. A range of around 80 miles is still impressive when you consider the size of the battery: 17.6kWh. That's thanks to its sheer size and lightness.


Environmentally-friendly plug-in hybrid cars

In theory, plug-in hybrid cars provide the best of both worlds, thanks to their large battery that can be charged up for several miles of electric-only motoring, along with an engine (usually petrol), which can take over when the electricity runs out.

On short journeys, fuel consumption can be negligible but long-distance travel will mainly use petrol power, bringing fuel economy much closer to a conventional car. Because the way that the car is used has such a big effect on fuel economy, the official mpg figures are almost useless when it comes to working out how much a car costs to run. However, they are a useful indicator of how environmentally friendly each one is, which is why we've used them to rank the plug-in hybrids below.

1. Mercedes A250e

Economy 282.5mpg CO2 22g/km CO 133mg/km NOx 37mg/km
Used deals from £30,590
Monthly finance from £444*

Gone are the days where plug-in hybrids could barely manage 20 miles - Mercedes promises to more than double this to 44 miles. It uses a 1.3-litre petrol engine and a 10.6kWh battery (over half the size of the one used in the electric Smart above!), and because it's only available in range-topping AMG Line trims, it's well-equipped. If the hatchback bodystyle doesn't work for you, Mercedes also uses the same setup in the A-Class Saloon, CLA and CLA Shooting Brake, GLA, and B-Class.


2. Renault Megane E-Tech PHEV

Economy 235.4mpg CO2 28g/km CO 261mg/km NOx 3mg/km
Used deals Limited stock

Renault has been hybridising its lineup recently, and so far the Clio, Captur, and Megane have been touched. In this instance, the Megane uses a 1.6-litre petrol engine and a 9.8kWh battery which can sustain the car for around 30 miles before it needs to be charged. The 'Sport Tourer' estate version was the first to get this treatment, but the hatchback has recently joined in on the action by offering the same plug-in hybrid setup.


3. Mercedes C300de

Economy 217.3mpg CO2 30g/km CO 24mg/km NOx 22mg/km
Used deals Limited stock

The C-Class uses a similar-sized battery to other plug-in hybrids - 13.5kWh - but this time, it pairs it with a 2.0-litre diesel engine. Although over 200mpg is very optimistic, drivers of the C300de can expect over 60mpg thanks to the diesel engine's efficiency at high speed, and the electric motor's efficiency at low speed. Just like with the A-Class above, Mercedes took what worked and applied it to other vehicles. As such, the GLC and GLC Coupe, and E-Class and E-Class Estate, all use the same setup.


4. Toyota Prius Plug-in

Economy 217.3mpg CO2 28g/km CO 28mg/km NOx 4mg/km
Used deals from £12,495
Monthly finance from £0*

We couldn't discuss hybrids, or plug-in hybrids, without including the original mainstream hybrid car. The latest version of the Prius Plug-in uses a 1.8-litre petrol engine paired to an electric motor powered by a relatively small 8.8kWh battery. Being rather light helps it to achieve a realistic 60-70mpg, although as with every plug-in hybrid car, keeping the battery fully charged and keeping within its electric-only range will significantly increase its efficiency. 


5. Volvo XC40 T4 PHEV

Volvo XC40 front three quarters view

Economy 134.3mpg CO2 41g/km CO 81mg/km NOx 11mg/km
Used deals from £25,900
Monthly finance from £0*

Volvo sells a pair of plug-in hybrid XC40s, the 211hp T4 and the 262hp T5. They both use a dual-clutch automatic gearbox, similar to the Hyundai Ioniq Hybrid and Ioniq PHEV, which some drivers may prefer to a CVT transmission that tends to be noisier; Toyota uses this type in its hybrid cars. They have similar efficiency figures, too, but the cheaper T4 will likely be enough for most people, with a 0-62mph time of 8.5 seconds. They combine a 1.5-litre three-cylinder petrol engine with an electric motor powered by a 10.7kWh battery.


Environmentally friendly hybrid cars

Toyota bills these cars as self-charging hybrids because you can't charge them up. Instead, their electric motors recover energy that's usually lost while braking, as well as from the engine when it's efficient to do so.

The electric power can be used to drive the car at slow speeds, but its main purpose is to assist the petrol engine during acceleration when fuel consumption usually soars. By reducing the effort required from the engine, battery power can make a significant contribution to fuel economy - particularly in traffic where speeds are constantly changing.

Toyota recently ran a test, spanning from April 2016 to June 2021, in which it completed over 137,000 test drives totalling 1.9 million miles in hybrid versions of its Yaris, Auris, Corolla, C-HR, Camry, Highlander, RAV4 and Prius cars. It concluded that up to 54% of a driver's time spent behind the wheel is spent in electric-only mode, which means in theory, hybrid cars are around twice as efficient and their petrol counterparts. 

1. Toyota Yaris Hybrid

Toyota Yaris Hybrid front three quarters view

Economy 68.9mpg CO2 92g/km CO 149mg/km NOx 10mg/km
Used deals from £8,299
Monthly finance from £0*

And here we are with another Toyota. Almost all of the company's cars are available with a hybrid setup, and the Yaris uses the smallest version. The bulk of the power comes from a 1.5-litre petrol engine, but as with most self-charging hybrids, don't expect to be able to travel very far on electric power alone. It comes into its own in stop-start traffic, allowing the engine to cut out in the name of efficiency.


2. Toyota Prius Hybrid

Economy 67.3mpg CO2 94g/km CO 97mg/km NOx 3mg/km

Used deals Limited stock

If you don't have access to a charging point, or the Prius Plug-in above is generally too expensive, the self-charging Prius could be a better option. Around town, where it belongs, you can expect to see around 60mpg, but take it on a longer journey and this could plummet to 40-50mpg. 


3. Toyota C-HR 1.8 Hybrid

Toyota C-HR Hybrid front three quarters view

Economy 58.9mpg CO2 109g/km CO 70mg/km NOx 4mg/km
Used deals from £15,200
Monthly finance from £0*

It's not just small cars that Toyota sells hybrid versions of. Whilst it's true that the RAV4 is available as both a self-charging and a plug-in hybrid, it uses a larger and less efficient 2.5-litre petrol engine. The same is true of the Highlander. This small crossover is better suited to a smaller engine, though, which in turn helps with efficiency. As ever, expect to hear the engine rev under pressure thanks to the CVT gearbox. 


4. Kia Niro Hybrid

Kia e-Niro front three quarters view

Economy 58.9mpg CO2 110g/km CO 160mg/km NOx 3mg/km
Used deals from £13,800
Monthly finance from £0*

If you prefer a dual-clutch transmission, but like the idea of a hybrid crossover, Kia's Niro is the perfect match for the C-HR. Like the Ioniq, it was developed with mother nature in mind, so its range comprises this self-charging hybrid model, a plug-in hybrid model, and an electric version. In the real world, it may be slightly less efficient, but where you lose some, you gain some, notably in interior quality and equipment levels. 


5. Lexus UX250h

Economy 53.3mpg CO2 120g/km CO 191mg/km NOx 5mg/km
Used deals Limited stock

Lexus is a premium brand that belongs to the Toyota group, which means plenty of experience creating hybrid setups. The UX250h uses a 2.0-litre petrol engine most of the time, as does the UX250h E-Four which places the electric motor on the rear axle, giving the car four-wheel-drive abilities. 

Environmentally-friendly petrol cars

1. Kia Picanto

Our pick Kia Picanto 1.0 66
Economy 58.9mpg CO2 110g/km CO 291mg/km NOx 13mg/km
Used deals Limited stock

Many drivers may not be ready to commit to electric power - partial or full - and prefer to stick to what they know best: petrol. The Picanto uses a no-frills 1.0-litre petrol engine; without a turbocharger, it achieves 66hp. Be aware, though, that as with most low-powered city cars, particularly those without a turbocharger, you may have to work the engine hard. Achieving the claimed 58.9mpg is very unlikely, as drivers are more likely to see less than 40mpg.


2. Kia Ceed

Our pick Kia Ceed 1.0 T-GDI 120
Economy 54.3mpg CO2 119g/km CO 249mg/km NOx 21mg/km
Used deals Limited stock

Putting a turbocharger on an engine is a sure way to increase the power - this 1.0-litre petrol engine produces almost double what the Picanto can produce. It may be a heavier car, but drivers should be less likely to need to push the car so hard, so over 40mpg should be possible.


3. Dacia Sandero

Our pick Dacia Sandero 0.9 TCe 90
Economy 53.3mpg CO2 120g/km CO 241mg/km NOx 29mg/km
Used deals Limited stock

This 0.9-litre turbocharged engine has been tried and tested across the Renault group (to which Dacia belongs). If you want one of these, but don't like the Sandero, you can find it used in the rugged-looking Sandero Stepway or Duster SUV, as well as Renault models like the Twingo and Clio


4. Mazda CX-3

Mazda CX-3 front three quarters view

Our pick Mazda CX-3 2.0 SKYACTIV-G 121
Economy 42.8mpg CO2 149g/km CO 234mg/km NOx 8mg/km
Used deals from £11,000
Monthly finance from £229*

Mazda's ethos is that a larger engine should have more readily available power, so drivers can opt for a gentler approach to acceleration. The company tends to use 1.5-litre and 2.0-litre petrol engines; in this small crossover, it's a 2.0-litre unit. You're unlikely to see 40mpg, but that's the tradeoff for having a larger, heavier car.


5. Honda Civic

Our pick Honda Civic 1.0 VTEC Turbo 126
Economy 47.1mpg CO2 135g/km CO 410mg/km NOx 12mg/km
Used deals Limited stock

Honda used to use larger engines, too, but often with turbochargers. With increased pressure to meet emission figures, this 1.0-litre turbocharged engine fits the family car well. It's a relatively new engine, though, so prices are likely to be quite high compared to less efficient petrols.


Environmentally-friendly diesel cars

An environmentally-friendly diesel car may have been a contradiction in terms a few years ago, but the very latest diesel cars have cleaned up their act. We can say that with more confidence thanks to new emissions tests that check how they perform in real-world driving, as well as in the laboratory.

The strictest tests at the moment are done to the Euro 6.2 standard (also known as Euro 6d-TEMP), which becomes mandatory for all new cars next year. Cars undergo a new, more comprehensive, laboratory procedure called WLTP and must meet limits on nitrogen oxide emissions both in the lab and during on-road testing.

We've ranked them on official mpg figures but, as ever, you should expect real-world fuel economy to lag behind because - unlike emissions - this is not officially tested outside the laboratory.

1. Renault Clio

Renault Clio front view

Our pick Renault Clio 1.5 Blue dCi 85
Economy 67.3mpg CO2 109g/km CO 53mg/km NOx 25mg/km
Used deals Limited stock

Renault has ditched diesel power, but before it did, it offered the Clio with a frugal 1.5-litre diesel engine. The Clio and Megane have been 90hp and 110hp versions of this engine, but the 85hp was the most efficient. Real-world scenarios could see the Clio easily achieve 60mpg, while NOx levels are low, too.


2. Peugeot 308

Our pick Peugeot 308 1.5 BlueHDi 130
Economy 65.6mpg CO2 113g/km CO 43mg/km NOx 46mg/km
Used deals Limited stock

Peugeot's successful range of diesel engines has helped it sell thousands, and the 1.6-litre diesel engine is no exception. With 130hp on tap, it feels rather punchy, but lightfooted drivers could achieve close to 60mpg relatively easily. Remember that diesel engines are most efficient at a low, but consistent, engine speed. Something like a long trip at an average speed of around 50mph. 


3. Mercedes A-Class

Our pick Mercedes A180d
Economy 64.2mpg CO2 115g/km CO 33mg/km NOx 59mg/km
Used deals Limited stock

Like the Prius, the A-Class appears on this list twice. Mercedes seems committed to reducing its cars' emissions - the A-Class was one of the first cars to adhere to the latest regulations. Both the A180d and A200d use a 2.0-litre diesel engine, so if you prefer a bit more power, you can open your search to include the slightly less efficient A200d too.


4. Alfa Romeo Giulia

Alfa Romeo Giulia front three quarters view

Our pick Alfa Romeo Giulia 2.2 JTDM-2
Economy 55.4mpg CO2 134g/km CO 29mg/km NOx 28mg/km
Used deals from £15,790
Monthly finance from £309*

This sporty-looking saloon is Alfa Romeo's answer to the BMW 3 Series, Audi A4 and Mercedes C-Class. While it can't compete on quality, it certainly holds itself behind the wheel. Driving enthusiasts will prefer the petrol version, but even the diesel version can be fun to drive, with a range of power outputs peaking at 190hp. 


5. Mazda CX-5

Our pick Mazda MX-5 2.2 SKYACTIV-D 150
Economy 51.9mpg CO2 154g/km CO 106mg/km NOx 51mg/km
Used deals Limited stock

The CX-5 was also an early adopter of the strict emissions regulations. The 2.2-litre diesel engine is a good match for this mid-sized SUV. It provides strong competition against the likes of the Volkswagen Tiguan and Skoda Karoq, thanks to its family-friendly five-star Euro NCAP rating.




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