The What Car? True MPG technicians test new cars every week. While the official Government figures come from a laboratory test, our team takes each car on a thorough road test that produces the data needed to deliver real-world MPG figures.
Here's our round-up of the most fuel-efficient small cars on the market today. All achieve more than 54.0mpg, with many returning more than 60.0mpg. The majority of the cars are diesel powered, but a petrol hybrid and a petrol city car also manage to make the cut.
1. Citroen C3 1.4 e-HDi 70 Airdream – official 83.0mpg: True MPG 70.3mpg
This diesel Citroen C3 is the only car in the list to return more than 70.0mpg. It might not be our favourite small car but a True MPG of 70.3mpg could prove very tempting to some buyers.
2. Citroen DS3 1.6 e-HDi 115 Airdream – official 74.4mpg: True MPG 63.0mpg
Another diesel Citroen but this time with a more powerful engine and a more stylish exterior. There's much to like about the DS3 including a classy cabin, generous specification and a True MPG of 63mpg.
3. Mini Cooper D 3dr – official 80.7mpg: True MPG 62.6mpg
The new Mini hatchback's official fuel economy figures are an improvement on the previous car's, and it is more efficient in the real world as well. The new Cooper D 3dr recorded a True MPG figure of 62.6mpg, although this is some way below the official rating of 80.7mpg.
4. Dacia Sandero 1.5 dCi – official 74.3mpg: True MPG 61.7mpg
The Dacia Sandero is not only cheap to buy but our data suggests it will also be cheap to fuel. Our testers recorded 61.7mpg against an official economy of 74.3mpg.
5. Fiat Panda 1.3 Multijet – official 72.4mpg: True MPG 61.0mpg
The Panda Multijet is the most frugal city car we've tested so far. Our technicians recorded 61.0mpg against official fuel economy of 72.4mpg.
6. Renault Clio 1.5 dCi 90 – official 78.5mpg: True MPG 60.1mpg
Renault's 1.5 dCi engine is also available in the Captur mini-SUV, but in the Clio it achieved 60.1mpg in our True MPG tests.
7. Vauxhall Corsa 1.3 CDTi Ecoflex – official 85.6mpg: True MPG 60.0mpg
The Vauxhall Corsa is spacious and well priced, and with this 1.3-litre diesel engine it's also economical.
8. Hyundai i20 1.4 CRDi – official 68.9mpg: True MPG 59.4mpg
Hyundai's latest i20 is well equipped and offers good value for money. The 1.4-litre diesel also manages to get pretty close to its official fuel economy figure.
9. Mini Cooper D 5dr – official 78.5mpg: True MPG 58.7mpg
The second Mini Cooper D to appear on this list is the new five-door version. It doesn't return fuel economy figures quite as impressive as its three-door relative, but it still manages to achieve a True MPG of 58.7mpg.
10. Ford Fiesta 1.6 TDCi Econetic 5dr – official 85.6mpg: True MPG 58.0mpg
Britain's best-selling car returns a respectable True MPG of 58.0mpg in 1.6 TDCi Econetic guise, but it's disappointing that it's so far off the official figure of 85.6mpg.
11. Toyota Yaris 1.5 VVT-i Hybrid – official 78.5mpg: True MPG 57.8mpg
If you want an efficient small car but don't want it to be diesel, the Toyota Yaris 1.5 VVT-i Hybrid could be the one for you. It's petrol-powered and returns a True MPG of 57.8mpg.
12. Skoda Fabia 1.4 TDI – official 83.1mpg: True MPG 57.7mpg
The diesel Skoda Fabia is one of the best small diesel cars on the market. It handles well, is cheap to run and has low company car tax rates.
13. Audi A1 1.6 TDI – official 74.3mpg: True MPG 57.1mpg
Audi's A1 is a former What Car? Car of the Year. Buyers are impressed by its premium feel and reliability. They'll also be pleased with the True MPG figure of 57.1mpg achieved by the 1.6 TDI models.
14. Volkswagen Polo 1.4 TDI – official 83.1mpg: True MPG 56.2mpg
The VW Polo has impressed our road testers, to the extent that it earned a five-star rating. It's not the most efficient small car, with its True MPG rating some way short of its 83.1mpg official figure, but 56.2mpg means you'll still travel a fair way between fills.
15. Toyota Aygo 1.0 VVT-i – official 65.7mpg: True MPG 54.0mpg
Another Toyota has made it into our round-up and this one is petrol-powered as well. The new Aygo is a striking city car that promises to be cheap to run thanks to its True MPG of 54.0mpg.
Visit whatcar.com/truempg to see the full range of cars we’ve tested to find out what you really can expect to achieve on UK roads.