The Interserie championship was founded in 1970 as European series similar to CanAm in North America. There were seen many CanAm cars such as McLaren, Lola, Porsche, March and BRM together with group 5 cars which were running in World Championship in the early years of Interserie. First champion Juergen Neuhaus started with group 5 Porsche 917 K but then became era of CanAm Turbo-Porsches followed by McLarens on top positions.
In 1976 cars of new group B6 running in two divisions made a new face of Interserie starting field. This was the end of Porsche era. Winners raced such cars like Lola, Sauber, TOJ and only in 1978 champion Reinhold Joest did his success with an old Porsche 908/3 Turbo.
This era started to finish in 1982 when new cars were admitted to start: new group C1 and C2 prototypes together with single seater Can-Am cars, which were usually build on F1 or F2 basics. But we could also see a 'real' Can-Am cars such as Holbert CAC 2 or March Chevrolet. In 1985 spiders of group B6 were definitely excluded and famous Porsche 956/962C began absolutely dominate in big division I. No one other was able to beat them until the first race of 1992 season. Charles Zwolsman has won in Mugello with his new Lola T 92/10 Judd. But he did not participate regularly, so in 1992 and 1993 most victories belonged to Porsches 962 GTP entered by Kremer and Joest.
But with the end of Sportscar World Championship in 1992, group C cars slowly started to disappear from top positions. Only older Spices, Tigas, Argos or other C2 cars were seen and they ran at the end of the field. From 1994 big teams with group C based cars definitely lost their interest about Interserie races and winners we could find between private drivers with F1 or IndyCar based Can-Am sportscars. The only exception was a very attractive Lola T92/10 Judd of Robbie Stirling from Canada, which was bought by McNeil Engineering and Robbie Stirling was the quickest Interserie driver in 1995-1997.
The first round of 1998 season had only 5 cars on the grid, so there was made an experiment in next races where ran together cars from Interserie and Austrian Euroserie.
For 1999 Interserie was run in new form. It became a club racing and got a new name: Interserie I.S.O. Sprint. All drivers had to be members of club I.S.O. Regulations were changed too. They now allow formula cars without covered wheels.