A woman in her 30s and the two youths were taken to hospital with serious injuries while a man in his 20s was treated for injuries not believed to be serious, after the crash in Birmingham in the early hours of Sunday.
West Midlands Police said a grey BMW X3 hit a tree and then a skip in Brandwood Road, Kings Heath, at just before 5am.
A statement from police said: "We're carrying out enquiries to establish what happened and are keen to hear from anyone who was in the area at the time.
"We're particularly keen for anyone who saw the vehicle prior to the collision and has dash cam footage.
"You can email us at FL_COLLISION_INVEST@westmidlands.police.uk or contact us via Live Chat on our website, quoting log 634 of February 5."