Also known as a 'paddy wagon', these were simply a basic form of police van adopted in the early days of automotive law enforcement by the Brits and the Americans. A particular brand of motor wasn't essential it was used primarily for space as they allowed multiple (and usually somewhat inebriated) suspects to be detained in the back.
Legend has it that the term 'Black Maria' is thought to come from an overbearing keeper of a sailors' boarding house who the police would call on to help them out with especially tough arrests. These days a modified Ford Transit or bus tends to do the trick.