The Yaris Hybrid is the most economical supermini on sale today – if you believe the claimed EU MPG figures – as well as the cheapest way into a hybrid. The 1.5-litre petrol-electric mix allows you reach a claimed 80.7mpg while only emitting 79g/km of CO2 and you get a decent amount of kit too, despite the usually expensive hybrid system. Prices start at around £15k. 

The more conventional Hyundai i20 comes close to the Yaris Hybrid on CO2, at 84g/km, but completely flaws it on economy. The tiny 1.1-litre three-cylinder diesel engine is claimed to achieve up to 88.3mpg, the best economy figure in our top five, on par with the Kia Rio. The i20 pips it – just - on both emissions and price, at £11,795.

The Kia Rio missed out on second place by just 1g/km of CO2. The Rio emits 85g/km but returns an equally impressive 88.3mpg from the same 1.1-litre diesel engine as the i20. At £11,895, it’s also £100 more than the i20 as well.

Peugeot’s new 208 uses a 1.4-litre diesel unit to achieve 83.1mpg, 2.4mpg more than the Yaris Hybrid, while producing just 87g/km. The 208’s freshs styling is the best of the bunch here, but we're after the lowest CO2 and it's doesn't come out top here.

Despite having the biggest engine in our top five, the Ford Fiesta ECOnetic 1.6 TDCi still emits just 87g/km. Although 78.5mpg is still a respectable economy figure, it’s the only supermini in our top-5 that fails to achieve over 80mpg and at £14,445, it’s also the second most expensive car here.