I see from the latest (official) announcements on the ST that it won't simply be a stretched version of the four-door.
There will be at least one new engine: an Ecomotive 1.6TDi, promising 85.6mpg and CO2 emissions of 88g/km. According to Autocar, this engine will be available for the three- and five-door Leons from January.
The ST will also offer adaptive suspension with "dynamic chassis control" (presumably as an option) as well as "progressive steering" and adaptive cruise control. At least some of these will be tied to the FR's Normal/Sport/Eco choices.
There will be at least one new engine: an Ecomotive 1.6TDi, promising 85.6mpg and CO2 emissions of 88g/km. According to Autocar, this engine will be available for the three- and five-door Leons from January.
The ST will also offer adaptive suspension with "dynamic chassis control" (presumably as an option) as well as "progressive steering" and adaptive cruise control. At least some of these will be tied to the FR's Normal/Sport/Eco choices.