The collision happened around 8.40am on the A8 in Port Glasgow, Inverclyde, forcing the closure of the road in both directions at the Newark Castle roundabout.
Those in the car were taken to Inverclyde Royal Hospital following the crash.
One of the five was seriously injured and is now in a stable condition at hospital, police said.
It is believed those who were injured were all men. The lorry driver is not thought to have been hurt.
Police Scotland said specialist scene examiners have been at the crash spot, which is near the A761.
It is understood and air ambulance was on the scene following the collision but was not required.