Mazda3 1.5 Skyactiv-D: 99g/km
In a sector dominated by the Ford Focus, Vauxhall Astra and Volkswagen Golf, you’d be forgiven for forgetting the Mazda3. But overlook it and you’ll be missing out on one of the sharpest looking and sweetest handling cars on the market. The 1.5-litre Skyactiv-D engine is a tad underpowered, but with CO2 emissions of just 99g/km, it takes the crown as the most efficient in the range. Buy now, or pay later.