Heading the list of upgrades for both models are 17in alloy wheels painted in Rock Metallic Grey, a honeycomb front grille and dark surrounds for the foglights. A lip spoiler is also added to the front bumper of the Fiesta, while the Focus gets a new bumper insert.
Inside, both models feature sports seats with red stitching and a perforated leather ST-inspired steering wheel. There’s also an ST-inspired gearknob, a dark, woven headlining and a set of ST-Line kick plates.
At launch, the ST-Line Fiesta range includes 1.0-litre three-cylinder EcoBoost petrol models with up to 138bhp and the 94bhp 1.5 TDCi diesel. ST-Line Focus models include the 1.0-litre EcoBoost engine with up to 123bhp and the 1.5-litre EcoBoost petrol unit with up to 182bhp.
Ford says two more engines are due to be added to the range in the coming months.
Prices for the Fiesta ST-Line kick off at £15,645, which is £251 more than the equivalent Titanium. The Focus ST-Line starts at £20,595, or £250 more than the equivalent Titanium.
Order books are open now, with first deliveries expected later this summer.