I reckon it's the Sehcar SH C6, which raced in 1983. It was Sauber based though I believe?
That's what it is! Built by Brun Racing and powered by a BMW M88/2 (whatever that is..........) . I'm sorry I didn't answer my previous post very helpfully - I should have hinted at the Sauber connection, but this car was a redesigned and rebuilt version.
A point to you.
(Yet again I show my lack of knowledge of anything after 1970!)