Actually you can still get to Hinges via the Surface Tool. Select Weld, click the surface. Then scroll down to properties, and select Hinge from the property tab. Understand though that eventually even this will be removed.
Also, the hinge won’t just auto-work anymore. You need the model to activate :MakeJoints. I uploaded a script that’ll do just that for you. Just drag and drop it into the model of the car in question.
(Like so:)
