Swiss cars are pretty rare. Swiss racing cars even rarer. All manners of Motorsport are outlawed in Switzerland since the 1955 Le Mans disaster.
But that didn't stop Peter Sauber from making his epic racing cars, which continue to do rather well to this day. The SHS C6 was the predecessor of the highly successful C9. The C6 used a Ford Cosworth engine when launched in 1982.
Only two SHS C6 chassis were made, later equipped with BMW engines. The last race they entered was the 1993 24 Hours of Le Mans - during which the remaining car crashed.
Matchbox had this casting in its line-up from 1985 to 1996 - initially in a somewhat correct BASF livery. This later "Bisotherm" livery seems to be the result of a promotional deal.
Bisotherm is real enough - but I can't find anything about them ever sponsoring any race cars.