Porsche has a proud rally heritage with memorable cars like the 959 Dakar and the more recent Cayman GT4 Clubsport Rally. Porsche Classic even went as far as developing two rally-ready Cayenne SUVs recently. But another one of the greats is the Porsche 924 Carrera GTS Rally.

In 1981, almost exactly 40 years ago, Walter Rohrl raced this car at the International ADAC Metz Rally. This special gold and black Porsche attained a second-place overall finish despite some vehicle issues and it remains the only rally season when Rohrl drove for Porsche. Porsche decided to embark on a top-secret restoration of the 924 as a 74th birthday surprise for Rohrl.

This Porsche was built in the Weissach motor racing department and this location was chosen as the site of its extensive restoration. The model chosen for restoration was built on 12 December 1980 and is said to be one of nine prototypes to be constructed at the time. The 2.0-liter turbocharged four-cylinder engine - mounted in front, unlike the 911 - has just over 10,000 km (6,214 miles) on the clock today and completed the 1981 rally season without sustaining any damage. As Porsche restorations go, the aim here was to achieve total originality. Although the gearbox was dismantled, it showed very little wear. The fuel supply system and some chassis parts were overhauled and reinstalled.

Pirelli had a set of tires on hand that maintained the tread of the period, while a race clutch was fitted from the Porsche Museum workshop. Porsche retained parts that reflected the car's age and demonstrated its originality; for example, the red seat belt harnesses were mildly faded from sun exposure but these were kept. The car even features the handwriting from the builders who originally put it together. For its rally use, this 924 received mods like underbody metal plates and a special fuel distributor from the 928's V8 engine.

Because Rohrl is so familiar with the Porsche facility and the people working there, it was a challenge for the team to keep the restoration a secret until the car was complete. However, they managed to keep 'Monnet' under wraps - Monnet was the cognac producer that inspired the gold/black paint.

Porsche pulled it off and presented the pristine 924 to Rohrl on his birthday in March. "It was a huge surprise for me," said Rohrl. I stepped out of the car 40 years ago and haven't sat in it again since. For me, it's a journey back in time."