I've read in several places that it's ok to use brauchen when you want to say it isn't necessary to do something, e.g.
Er braucht nicht die Bücher zu lesen.
But I'm struggling to find a reference anywhere to using it in this quasi-modal manner for something that it is necessary to do, e.g.
I need to buy a new car.
Should we just use müssen or es ist mir nötig?