What is it?
It’s when you can’t stay in sixth gear on a flat surface through a 50mph motorway roadworks without its engine grumbling about the load, at well under 2000rpm, that you realise where the i20 Blue finds some of its ability to return 76.4mpg on the combined cycle.
This leggy gearing is no higher than the standard 89bhp diesel variant of the i20 supermini. But it makes the 111g/km car the ideal starting point.
From there, Hyundai adds stop-start, a rear wheel wind deflector and an underfloor cover for the rear suspension. When I was a lad studying engineering, I was told that up to 30 per cent of a car’s aerodynamic efficiency comes from underneath it, so this stuff can make a big old difference.
So, too, do low rolling resistance tyres, with the upshot that the i20 Blue has emissions 12 per cent lower than the standard Comfort trim on which it’s based. Its 98g/km is the lowest in Hyundai’s range. And although it’s 3g/km higher than a Ford Fiesta Econetic, it’s also £1300 cheaper and still gets you free road tax. It’s pretty well equipped, too.