Haven't seen any mention of the car being pursued
No, not on this occasion. The driver had been in a police pursuit prior though (he had not long been released from jail for drugs charges & he was caught after a high speed pursuit in which I believe he travelled as speeds over 100mph).
That area is a rat run for boy racers, so it wouldn't surprise me if he was travelling at significant speed even if he wasn't being pursued. It was also icy & foggy (if I remember the night correctly). The gritters had been out several hours prior to the accident, but even so, it wouldn't have been safe enough for fast driving.
There's a lot of CCTV in the area, so I think what ever happened would likely have been caught on camera, as well as witnesses from other vehicles in the area. It could just be that in this case, the police are being able to keep the details away from the press until the coroners reports and other inquiries are done, at which point I'm sure there'll be a proper statement.