car·jack or car-jack 
(kärjăk′)
(kärjăk′)tr.v. car·jacked, car·jack·ing, car·jacks or car-jacked or car-jack·ing or car-jacks
To take or attempt to take (a motor vehicle) from another person by use of force or intimidation.
[CAR + (HI)JACK.]
carjack′er n.