The Aston Martin Rapide S has been spied near the Nurburgring in Germany as the UK-based luxury sports car maker prepares a hotter version of its flagship ‘four-door coupe’ for showrooms.

CarAdvice’s spy photographers first captured this pale blue Rapide prototype at the ’Ring more than 12 months ago although its fine-tuning is believed to have taken a backseat to the development of the new Aston Martin Vanquish sports car.

Now that the Vanquish has been unveiled, the focus has shifted back to the Rapide S, which has progressed to a near-production-ready state and is testing on public roads.

With its sights set on the 294kW Porsche Panamera S, the Rapide S will employ an enhanced version of the standard car’s 6.0-litre V12 engine, elevating power from 350kW to 370-385kW. The extra ponies should see the Rapide S accelerate from 0-100km/h in just under 5.0 seconds.

Joining the more powerful engine will be a modified chassis with bigger brakes and stiffer suspension, creating a more purposeful and better-handling overall package.

Visually, the Rapide S scores a larger grille and a thinner, wider lower air intake. Unique alloy wheels are evident in its profile while the rear will get mildly revised tail-lights and a larger spoiler sculpted into the boot lid.

Aston Martin is expected to officially unveil the Rapide S before the end of the year, with deliveries set to commence in 2013. Its price is unconfirmed at this stage but will exceed that of the standard Rapide, which starts at $371,300.