Would you leave all your worldly possessions in a car in a parking garage?

…for a few hours on a weekday? To be specific, the city is Boston and the garage is Alewife. I’m moving tomorrow but have to stop in Boston to do some stuff so I’m going to leave my car. I had hoped it would all fit in the trunk so it’s not obvious that it’s full of stuff but that will be impossible.

Do parking garages connecting to metro systems generally have any security?