The 5cyl Volvo engine was a BRAND new design when it was introduced in the 850. It was one of the first mass production engines to have a engine block from aluminium(or at least something like the only engine in it's segment to be solely made of aluminium or something... The Rover V8, which was based on the Buick 215 V8 from the '60ies, was also an all aluminium engine).

The Volvo 5 cyl engine has nothing whatsoever to do with the Audi engine, or the old 4 cyl Volvo engines for that matter. The newer Volvo 4 cyl engines might be deratives of the 5 cyl Volvo, but it was the 5cyl engine that was first.