Found this info on this site:
Porsche 911 Turbo 3.3 Martini RHD. For Sale (1978)
One of three now known to exist. GP white with Martini special edition leather trim. Martini stripes, turbo Fuch alloy, electric roof, aircond. Full documented history from new. In concours champion winning condition. Very rare and special Porsche in as new condition. £79,950.
Wow.... still worth quite a bit of money....