The 34-year-old man, from Blackburn, collided with the central barrier near northbound Junction 35 (Carnforth, Morecambe) at around 3pm yesterday (Wednesday, January 16).
The man escaped from the mangled BMW and ran across three lanes of traffic on the busy carriageway to the relative safety of the hard shoulder.
But as the man stood behind the barrier on the hard shoulder, a Skoda Octavia, also travelling northbound, crashed into him.
The man suffered a serious head injury, fractures to the upper body and internal injuries.
He was taken by Air Ambulance to Royal Preston Hospital for treatment where he remains in a serious condition.
The driver of the Skoda, a 41-year-old man from Edinburgh, was not injured.
The two serious incidents were among a number of collisions close to Junction 35 on Wednesday.
Eight other vehicles were also involved in collisions around the time of the incident on the northbound carriageway.
The M6 was closed northbound for six hours while accident investigators attended the scene and the stricken vehicles were recovered.
A second collision, involving five vehicles on the southbound carriageway, also happened around 3pm.
No serious injuries were reported and the road re-opened a short time later.
Police are appealing for information following the incidents, including dash cam footage of the collisions.
Sgt Steve Hardman, of Lancashire Police, said: “We are investigating a serious collision on the M6.
“A number of vehicles were involved, with one man suffering serious injuries.
“We are appealing to anyone with information to come forward.
“We understand there were exceptional weather conditions during the time of the collisions and would ask anyone with dashcam footage to come forward.
“Furthermore, if you helped to move any of the vehicles involved to the hard shoulder before police arrived, please get in touch.”
Anyone with information can contact police on 101 or email [email protected] quoting log 0843 of January 16.