Jim
It's a Group 4/5 blend. It's a real racing oil sold by BMW for the "M" engines, but it originates with the BMW Motorsport division for use in their racing program. "Formula BMW" engines use it, and the M3 GTR V8 used it.
It's too bad people tend to slag it because the dealers sell it - it's vastly better than most of the "upscale replacements".