Vauxhall is keen to dispel any ideas that the GTC is only a three-door Astra, so it has released technical details of its new sporting model ahead of the launch.

The Astra GTC will be an entirely separate model and the chassis has been tuned for the keener driver. Much of this work has been carried out in the UK at Vauxhall's Millbrook proving ground and on UK roads.

A HiPerStrut very similar to the one used on the Insignia VXR will be used on the GTC to cope with power outputs from 120- to 180bhp. More powerful engines are expected to join the GTC line-up as Vauxhall adds hot VXR-badged models.

Michael Harder, the engineering supervisor for vehicle dynamics for the GTC, said: "Our aim was to exceed the best in class with the GTC's dynamics. We also wanted to change the emphasis in steering and damper feel from the regular Astra 5-door to a set-up that was more focused, yet still comfortable enough for the most demanding roads in Europe and the UK."

The HiPerStrut helps to reduce torque steer and improves steering feel, while at the rear of the GTC, the Watts linkage has been altered to create a lower ride height and wider track.

The GTC will come with 18-inch alloy wheels as standard, which can upset ride quality. Gary Baker, chief dynamicist at Vauxhall's Engineering Centre, said: "The UK road system is like no other in Europe. We obviously test cars in many different countries, but the UK's severely undulating and heavily cambered roads often reveal handling traits that would otherwise be hidden on smoother surfaced and more predictable continental roads.

"It's not just the surfaces, either. Corners with changing radii are commonplace in the UK, as are blind apexes and crests, which mean that extra demands are put upon our cars and drivers."

The Vauxhall Astra GTC goes on sale in the UK towards the end of 2011 with prices starting at £18,495.

Alisdair Suttie - 22 Jul 2011