The Rotella Syn 5W-40 is SM rated and good for gas engine use. I use it in our Land Rover. The T6 is a great oil, readily available and priced well. But with the other European cars, most manufactures, not all (like our LR), have a specification of what the oil is required to do based on R & D and based on that, oils are approved by the manufacture for use in a specific application. Not just anyone can claim their oil meets those specs. It costs big $$$ to get the engine approval.
I'm not saying the T6 won't meet or exceed certain Euro car requirements, it's just there isn't any value in getting the approvals for that oil since we have many products that already do so (QSUD Euro, QSUD Diesel VX, Plat Euro, Plat VX, Ultra) and meet a laundry list of both gasoline and diesel engine specs for PCMO.
The T6 syn can be used really in anything within reason. Has a really robust additive package and provides some extra protection for cars with a little mileage on them, towing applications and high powered engines.