On 1 March 1970 the 914/6 was homologated by the Fédération Internationale de l'Automobile (FIA) for Group 4, Special Grand Touring cars.
That same month two cars were sent to the Targa Florio for testing, not as competitors.
These were the first two 914/6 GT cars built.
Externally the cars were distinguished by squared fender flares that were the full 2 in (51 mm) depth permitted by FIA rules.
The chassis was reinforced with three welded plates on each side.
For rally applications a stone guard protected the power-train and a stone shield did the same for the front of the car.

The GT cars received stronger lower front A-arms, and anti-roll bars were fitted front and rear.
Ground clearance was reduced to 4 in (102 mm).
Brakes front and rear were upgraded to the same components used on the racing 911S model.

Fiberglass panels for the front and rear bumpers, front and rear deck lids, and left and right rocker panels replaced the original steel parts.
The rear air intake grille was doubled in size.
An inlet in the front bumper admitted air to a new supplementary oil cooler in the nose.
The car's nose compartment was nearly filled by a 100 l (26.4 US gal) fuel tank.
The car weighed 1,980 lb (898.1 kg) ready to race.

The engine remained at 2.0 litres displacement with Weber carburetor induction, but was extensively upgraded otherwise.
New cylinder heads with larger valves topped aluminum cylinder barrels with chrome-plated bores.
A dual-ignition system fired two spark plugs per cylinder.
High compression pistons and forged steel piston rods were borrowed from the 911S. A special crankshaft was added.
Camshafts and rocker arms came from the 901/20 in the Carrera 6.
Power output was up to 210 PS (154.5 kW; 207.1 hp) at 8000 rpm.

Although the factory campaigned the car in rallying, it was more successful in road racing.

In the United States the Porsche+Audi distributor called the car the 914/6R.
On 1 March 1970 the 914/6 was homologated by the Fédération Internationale de l'Automobile (FIA) for Group 4, Special Grand Touring cars. That same month two cars were sent to the Targa Florio for testing, not as competitors. These were the first two 914/6 GT cars built. Externally the cars were distinguished by squared fender flares that were the full 2 in (51 mm) depth permitted by FIA rules. The chassis was reinforced with three welded plates on each side. For rally applications a stone guard protected the power-train and a stone shield did the same for the front of the car.
The GT cars received stronger lower front A-arms, and anti-roll bars were fitted front and rear. Ground clearance was reduced to 4 in (102 mm). Brakes front and rear were upgraded to the same components used on the racing 911S model.
Fiberglass panels for the front and rear bumpers, front and rear deck lids, and left and right rocker panels replaced the original steel parts. The rear air intake grille was doubled in size. An inlet in the front bumper admitted air to a new supplementary oil cooler in the nose. The car's nose compartment was nearly filled by a 100 l (26.4 US gal) fuel tank. The car weighed 1,980 lb (898.1 kg) ready to race.
The engine remained at 2.0 litres displacement with Weber carburetor induction, but was extensively upgraded otherwise. New cylinder heads with larger valves topped aluminum cylinder barrels with chrome-plated bores. A dual-ignition system fired two spark plugs per cylinder. High compression pistons and forged steel piston rods were borrowed from the 911S. A special crankshaft was added. Camshafts and rocker arms came from the 901/20 in the Carrera 6. Power output was up to 210 PS (154.5 kW; 207.1 hp) at 8000 rpm.
Although the factory campaigned the car in rallying, it was more successful in road racing.
In the United States the Porsche+Audi distributor called the car the 914/6R.
Porsche 914