Environmentally-friendly cars

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

BuyaCar team
Oct 16, 2018

Buying an environmentally-friendly car doesn't mean you have to buy an electric vehicle - although that's not a bad move.

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 miles of electric driving before the engine is needed.

The introduction of new, tougher emission tests over the past year 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. It means that the most environmentally-friendly cars are likely to be fairly new, 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 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.

Are smaller engines more environmentally-friendly?

Not always: small engines between 0.9 and 1.2 litres in size tend to rely on turbochargers, which force more air into an engine's cylinders, increasing power without much more fuel. However, the heat from this process tends to produce higher levels of toxic nitrogen oxides. In larger, heavier cars, small engines usually need revving hard to get up to speed, which dramatically increases fuel use. As a result, some manufacturers, such as Renault and Nissan are starting to produce larger engines. 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

It's frequently being pointed out that electric cars don't get their energy out of thin air (unless they are solely using wind power, of course), so it makes sense to buy one 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.

1. Hyundai Ioniq 5.4 miles per kWh

Latest Hyundai Ioniq PHEV deals from £21,850
Finance from £326 per month

Despite being spacious enough for a family, Hyundai's Ioniq is the most efficient electric car on the market, according to official figures. These reveal that the car uses half as much electricity per mile as the Tesla Model X, reducing the amount of electricity it needs and increasing the range, which - in real world driving - is around 140 miles between charges.
Hyundai Ioniq buying guide


2. Volkswagen e-up! 5.3 miles per kWh

Latest VW e-up! deals Limited stock. Click for prices

One of the smallest electric cars on the market comes close to being the most efficient, which is just as well. Adding any more batteries would have increased the cost further, beyond the current new price of almost £20,000.

The limited range of between 75 and 100 miles, depending on temperature and driving style, is easily enough for town driving, but it does restrict the up! on longer journeys. Combined with the high price, it struggled to attract buyers, which means that used examples are few and far between.


3. Volkswagen e-Golf 4.9 miles per kWh

Latest VW e-Golf deals from £19,000
Finance from £278 per month

The Golf doesn't just look like a conventional car, most people will find that they can use it like one too, thanks to a real-world range of 120 miles, which is achievable without driving it any differently to a petrol or diesel vehicle.

The car's efficient use of electricity is a key factor in its performance, even if it's somewhat short of the official 186 mile range figure that came from laboratory testing.


4. BMW i3 4.9 miles per kWh

Latest BMW i3 deals from £17,992
Finance from £274 per month

BMW's i3 is designed as an electric car from the ground up, and you can tell. Instead of steel or aluminium, it's mainly made from lightweight and strong carbon fibre, which reduces the weight that the motors need to pull around.

As a result, the car's efficiency is up with the best and an updated car that goes on sale in December will bring bigger a bigger 120Ah battery pack, increasing its range from the 125 miles that you can typically expect (again, well short of official figures) closer to 200 miles.


5. Smart EQ ForFour 4.8 miles per kWh

Latest Smart Electric deals from £5,000
Finance from £88 per month

Both the two-seat Smart ForTwo and four-seat ForFour electric versions are equally efficient, and it's not difficult to see why they are close to the top of this list: there's not a great deal of car for the electric motors to haul around, and the small battery pack hold less power than the Volkswagen up!.

Unfortunately, this lack of battery capacity brings the realistic range of the ForFour down to below 70 miles, which makes it fine for small city journeys but will have you constantly on the lookout for charging points if you stray more than a few miles from home.


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. BMW i3 ReX 470.8mpg

Latest BMW i3 ReX deals from £17,992
Finance from £281 per month

BMW's i3 Range Extender (ReX) works in a slightly different way to most plug-in hybrids (PHEVs) because it uses a petrol engine to recharge the battery when it's low, meaning that the car's motors are always driving it.

As it's based on the pure electric i3, the range on battery power is much greater than with other PHEVs, meaning you'll be able to run on electricity far more, and making it the most efficient plug-in hybrid. However, this will no longer be available as a new car, as BMW is increasing the battery size of the standard i3 from December, making the ReX model redundant.


2. Toyota Prius Plug-in - 283mpg

Latest Toyota Prius Plug-in deals from £18,799
Finance from £249 per month

The Prius' high place in this table is well-justified because it's eefficient, even when the battery finally runs out after between 25 and 30 miles of electric power. On long journeys, this means that you can expect between 60-70mpg, which would be good for a diesel engine, let alone a petrol car.

The secret is a gearbox that's tuned for efficiency - not performance - and a smooth shape that reduces wind resistance, along with the amount of energy required to keep it rolling along.


3. Hyundai Ioniq PHEV - 256.8mpg

Latest Hyundai Ioniq PHEV deals from £21,850
Finance from £326 per month

With a electric-only range of around 30 miles, the Hyundai Ioniq compares well to the Toyota Prius Plug-in, and that's before you even look at its superior interior and boot space.

Howevr once the battery runs out, the Ioniq falls behind on fuel economy. Whereas you can expect around 60mpg from the Prius, this Ioniq will return between 45mpg and 50mpg, which is still economical - just not the best.
Hyundai Ioniq buying guide


4. Kia Niro PHEV - 217.3mpg

Latest Kia Niro PHEV deals from £21,500
Finance from £309 per month

Tall cars that provide a lofty driving position are ever-more popular but the blocky design doesn't do much for fuel economy. Kia's managed to offer the best of both worlds, thanks to a smooth design and an efficient plug-in hybrid system that prioritises mpg over everything else.

This means that acceleration is slow and the petrol engine frequently starts up to assist the motor (it can be more efficient to run both together on longer trips).


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.

1. Toyota Prius - 94.1mpg

Latest Toyota Prius deals from £16,443
Finance from £210 per month

With more than two decades of experience selling hybrid cars, Toyota's expertise in the area is clear. The latest version of the Prius is an excellent car in its own right, with a spacious interior and smooth ride. The excellent fuel economy is a bonus. And although you can forget the official 94.1mpg figure, 70mpg is not unrealistic if you're driving in town, which is better than any diesel alternative.
Toyota Prius buying guide


2. Toyota Yaris - 85.6mpg

Latest Toyota Yaris hybrid deals Limited stock. Click for prices

The small size of the Yaris, combined with Toyota's hybrid system, makes for an extremely efficient car, which is also excellent value on the used market. Like the Prius, it excels in stop-start driving, and you're likely to get 70mpg from the car in urban driving. 

At higher speeds, and over longer distances, the advantage of the hybrid system weakens, and fuel economy is closer to the 45mpg of standard petrol Yaris models.
Toyota Yaris buying guide


3. Toyota Auris - 80.7mpg

Latest Toyota Auris hybrid deals Limited stock. Click for prices

Toyota's Auris is a car that's meant to impress you with its practicality, which is a polite way of saying that it's not particularly interesting - a situation that's likely to change with the arrival of its replacement, which will be badged Corolla, next year.

The hybrid car is some way off the efficiency of the Prius, but is much less expensive to buy as a used car, which is likely to make the cost of running one cheaper in the long run.
Toyota Auris buying guide


4. Lexus CT200h 78.5mpg

Latest Lexus CT deals Limited stock. Click for prices

A so-called luxury hybrid model, this Lexus is yet another car to use Toyota's hybrid system for excellent efficiency, particularly in town.

It's an interesting option as a used car, thanks to the affordable prices of older models, and reasonable choice. Compared with newer alternatives, however, the CT200h is less strong; the unsettled ride is sometimes uncomfortable on British roads and the interior was clearly designed more than a decade ago.
Lexus CT200h buying guide


Kia Niro 2 hybrid 76.3mpg

Latest Kia Niro deals from £14,999
Finance from £219 per month

The only car here that doesn't use Toyota's hybrid system, the standard hybird Kia Niro has an impessive headline mpg figure, but its tall shape and weight count against it at steady speeds, when the battery can't recover a great deal of power.

In this scenario, real-world fuel economy is around 45mpg, which isn't a great deal better than some of the more efficient standard petrol cars.
Kia Niro buying guide


Environmentally-friendly petrol cars

Smart ForTwo 71hp - 68.9mpg

Latest Smart ForTwo deals from £6,098
Finance from £112 per month


Toyota Aygo 1.0 VVT-i - 68.9

Latest Toyota Aygo 1.0 VVT-i deals from £4,700
Finance from £82 per month


Citroen C1 1.0 VTi 68 - 68.9mpg

Latest Citroen 1.0 VTi deals Limited stock. Click for prices


Peugeot 108 1.0i 68 68.9

Latest Peugeot 18 1.0i deals Limited stock. Click for prices


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.

The cars below passed these tests and recorded nitrogen oxide emissions of 40mg/km or less (in lab conditions), which is half the of the maximum allowed. Carbon dioxide emissions are under 110g/km too - well below the average for a new car. Most of the cars use AdBlue; an additive that reduces emissions, which will need topping up.

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.

All of the cars below passed the latest tests in 2018, but most were on sale before then. This means that it may be possible to buy older used models that aren't certified to the Euro 6.2 standard. Their emissions may not match those of the newer cars.


Peugeot 308 1.5 BlueHDi 130 EAT8 - 78.5mpg

Latest 2018 Peugeot 308 diesel deals from £9,995
Finance from £167 per month

An updated version of the Peugeot 308 arrived at the beginning of 2018, with a new 1.5-litre BlueHDi diesel engine that meets the Euro 6.2 standard. The 308 SW estate version offers similar fuel economy and the same emissions standard, as well as the hatchback pictured above.

While it might be clean, the car can't live up to the official fuel economy figures: it's likely to return around 51mpg in normal driving, according to the independent Equa Index, which estimates realistic mpg figures based on its own road tests.


Citroen C3 BlueHDi 100 - 76.3mpg

Latest Citroen C3 diesel deals (current model) from £6,619
Finance from £119 per month

Citroen's C3 hatchback has been on sale since 2017, so there are plenty of used examples available but its BlueHDi 100 diesel engine was only certified to the latest Euro 6.2 standard in July 2018, just ahead of the C3 Aircross - a taller version of the car, which is available with the same engine.

Officially, its mpg figure is lower than the Peugeot 308 that's above it in this list, but the car's real-world fuel economy is much better, approaching 60mpg.


Peugeot 508 1.5 BlueHDi 130 - 74.3mpg

The new Peugeot 508 is available with the same 1.5-litre BlueHDi engine that's fitted to the Peugeot 308. Unsurprisingly, it too complies with the latest Euro 6.2 standards and falls similarly short when it comes to real-world fuel economy: 50mpg is roughly what you can expect.

Used versions of this latest car are few and far between at the moment, but it's available to order from new.


DS 7 Crossback BlueHDi 130 - 72.4mpg

Latest DS 7 diesel deals from £22,185
Finance from £311 per month

Citroen, DS and Citroen are all part of the same PSA group, and they all share the same engine technology. So it's the third appearance for the company's 1.5-litre BlueHDi engine.

It's been compliant with the Euro 6.2 emissions standard since the car first went on sale, as has the car's larger 2-litre diesel engine and the two petrol engines, so you can be sure that any used DS 7 is relatively environmentally-friendly. Just don't expect to see fuel economy that's anywhere close to the official figure.


Kia Stonic 3 1.6 CRDi - 70.6mpg

Latest Kia Stonic 1.6 CRDi deals from £11,690
Finance from £173 per month

The only non-French car in the top five at the moment, Kia's 1.6 CRDi diesel engine in the Stonic passed the Euro 6.2-standard test in August 2018. Fuel economy in public road driving is reasonable at around 52mpg, according to the Equa Index, but some way off the official figures.


Read more about:

Latest car buying advice

  1. Cash vs finance: how to budget for a car

  2. Cheaper used car tax: road tax rules before April 2017

  3. Second-hand HP (Hire Purchase finance)

What our customers say