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Top 10 cars for low CO2 emissions

Which? reveals the cars with the lowest emissions

car emissions

Earlier this month we revealed the European Commission’s plan to reduce CO2 emissions from new cars by 2020 to an average of 95g/km. But why wait until then to save money on car tax (VED)? 

Each and every car that passes through our test lab undertakes an environment and eco test. Not only do we record more accurate fuel economy figures than manufacturers, but we also measure real-world exhaust emissions.

Here we reveal the top 10 cars we’ve tested that come closest to hitting the 2020 CO2 target, including one that surpasses it – all of these cars cost £20 or less in car tax each year.

1. Peugeot iOn – 88g/km

As a fully electric car, nothing actually comes out of this vehicle while it is being driven, but CO2 is released through the production of the electricity used to charge it. We used the latest figures from the Department for Energy and Climate Change, which state that an average of 521 grams of CO2 are emitted per kilowatt hour of electricity, to calculate the iOn’s CO2 emissions.

VW Polo

2. Volkswagen Polo – 99g/km

All the VW Polos we’ve tested have low emissions, but it’s the 1.2 TDI BlueMotion diesel that emits the least at 99g/km. This is exceptionally good and contributes to low running costs. In contrast, the 1.4-litre petrol engine is the worst Polo we’ve tested for emissions, recording 140g/km.

3. Vauxhall Ampera – 102g/km

The Ampera is a ‘range-extender’ hybrid. This means is can run on electricity with no range anxiety, as it also has a petrol engine. Short distances can be completed in electric mode only, so there are zero emissions. However, according to our tests of the car in combined electric/petrol mode, it actually emits 102g/km of CO2.

Smart ForTwo

4. Smart ForTwo – 105g/km

The Smart ForTwo is one of the world’s most recognisable city cars. It’s only got two seats, but is surprisingly spacious for its driver and passenger. The 0.8 CDI engine promises low carbon dioxide emissions levels, and it recorded 105g/km in our tests. However, the official manufacturer CO2 claim is 88g/km, so this car still benefits from free road tax.

5. Nissan Leaf – 106g/km

One of the first battery-driven, family-sized cars available in the UK, the Leaf offers low running costs. Using the same system as the Peugeot iOn, we measured the emissions at 106g/km. However, the precise CO2 output of the car will vary depending on exactly how it is charged. For example, if charging is supplemented by solar power, then that figure will be lower.

VW Golf

6. Volkswagen Golf – 108g/km

The VW Golf has a wide range of emissions depending on which engine you opt for. The 1.4 TFSI recorded a lofty 160g/km. However, the 1.6TDI BlueMotion impressed our experts with only 108g/km CO2 emissions, which ensures car tax is kept to a minimum.

7. Toyota Auris – 109g/km

Toyota launched this hybrid version of its Auris back in 2010. The Auris hybrid is smooth and quiet, and has so far proved very reliable. As for emissions, there is still some work to be done to hit the 2020 target, but at 109g/km it is one of the best performers at present.

Honda Insight

8. Honda Insight – 111g/km

Rivaling the Toyota Prius in the large cars class, the Insight hybrid has an efficient 1.3-litre engine. CO2 emission claims of the latest Insight are between 96g/km and 99g/km (bettering the original version’s 101g/km), however our tests recorded 111g/km.

=10. Audi A1 – 111g/km

Taking manufacturer claims, no Audi A1 has official C02 emissions of more than 125g/km, meaning you’ll pay no more than £95 a year in tax. The most efficient engine we’ve tested is the 1.6 TDI – measuring 111g/km, 8g.km higher than the claim.

Toyota Prius Plugin

=10. Toyota Prius Plug-In – 111g/km

The brand new Prius Plug-In builds on the original Prius’s eco-friendly reputation. The hybrid petrol-electric 1.8-litre engine offers electric-only driving at speeds up to 62mph. But, once the petrol kicks in, emissions increase to a recorded 111g/km.

More on this…

  • New CO2 targets – read all about the new CO2 emission targets
  • Eco cars rated – see our guide on all the electric cars we’ve tested
  • Petrol vs diesel fuel costs – calculate the cost of running a petrol car against a diesel
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