The fatal collision happened on the northbound motorway, past Tebay services in Cumbria, at around 4pm on Tuesday.
Four occupants of the Toyota—a man, a woman, and two children from Glasgow—were pronounced dead at the spot.
A Cambridgeshire guy who was driving the Skoda also perished in the collision.
According to Cumbria Constabulary, a third youngster in the Toyota was sent with critical injuries to Newcastle’s Royal Victoria Infirmary.
A stretch of the M6 northbound between J36 and J39 was closed following the crash but reopened fully in the early hours of Wednesday.
A force spokesperson said: “The families of those involved are being supported by specially trained officers.”