The new Fiesta ST couldn’t have bigger shoes to fill.

The current one became an instant classic and its status as the world’s best compact hot hatch has remained intact for four years.

2017 Ford Fiesta ST officially revealed

Its four-cylinder engine played an important part in that standing, and although the transition to a three-pot is understandable, its success is far from guaranteed.

Notably, Ford hasn’t opted to increase the power. Leaving aside overboost possibilities, the new petrol motor only equals the peak output of its ST200 predecessor. Without going to the expense of fitting a limited-slip diff, that’s probably sensible. But nor has the 0-62mph time improved, so the Fiesta has potentially gained little from a presumed cut in mass.

Failing to increase performance doesn’t stop the car from being brilliant, but a failure to close the gap to more expensive options, such as the Mini Cooper JCW, risks it looking like a second-class citizen to some buyers.

Still, no one is likely to complain about the engine’s efficiency advantage. CO2 emissions of 114g/km ought to put the ST’s combined claim at about 55mpg — not too shabby for fast supermini. But delivering the sound, burliness and high-rev reward of the Ecoboost will be the real achievement.