The most notable engine in the line-up is the 108bhp 1.6 TDI in the Ecomotive version. This model, with CO2 emissions of 88g/km and 85.6mpg economy, is the most frugal yet in the Leon range. Ecomotive versions of the three-door and five-door hatches, with the same economy figures, will also be rolled out in January.
The Leon ST is the first Leon to be offered with adaptive suspension with the so-called Dynamic Chassis Control, something that will be rolled out across the rest of the range alongside what Seat is calling 'progressive steering.'
Other engines include a 1.2 TSI with 85bhp or 104bhp, a 1.4 TSI with 120bhp or 138bhp and a 178bhp 1.8 TSI in the range-topping petrol FR. Other diesel options include an 89bhp 1.6 TDI and 148bhp and 181bhp versions of the 2.0 TDI.
The Leon ST, when combined with the smallest 1.2 TSI engine weighs just 1158kg, making it the lightest car in its class.
Seat boss Jürgen Stackmann said: "The C-segment estate market is the third biggest in all of Europe, some 520,000 cars of 11.7 million sold last year were in this segment. So it's not a niche for us, and an important segment for us to be in.
"We want to be the most beautiful car in the segment but with no compromise on practicality. This is the first car to combine both."
The Leon ST is a completely new design from the B-pillars back and, although the wheelbase remains the same as the five-door hatch, chief designer Alejandro Mesonero-Romanos is pleased with the result: "buying a car like this used to be only for families, but those days are over. The choice in the segment is usually for style and sporty, or you have to compromise. People are demanding, wanting practicality and style, and if you fail at either or both than you reduce your chances of success, but we've shown that both are possible."
Seat Leon ST prices:
Seat Leon ST S 1.2 TSI 105 – £16675
Seat Leon ST S 1.6 TDI 105 - £18375
Seat Leon ST SE 1.2 TSI 105 - £17795
Seat Leon ST SE 1.2 TSI 105 DSG - £19045
Seat Leon ST SE 1.4 TSI 140 - £18845
Seat Leon ST SE 1.6 TDI 105 - £19495
Seat Leon ST SE 1.6 TDI 110 Ecomotive - £20485
Seat Leon ST SE 1.6 TDI 105 DSG - £20745
Seat Leon ST SE 2.0 TDI 150 - £20845
Seat Leon ST SE 2.0 TDI 150 DSG - £22095
Seat Leon ST FR 1.4 TSI 140 - £20390
Seat Leon ST FR 1.8 TSI 180 - £21595
Seat Leon ST FR 1.8 TSI 180 DSG - £22845
Seat Leon ST FR 2.0 TDI 150 - £22390
Seat Leon ST FR 2.0 TDI 150 DSG - £23640
Seat Leon ST FR 2.0 TDI 184 - £23380