MPV is 'multi-purpose vehicle', but generally refers to 'people carriers', or cars carrying over 5 people (or with 3 rows of seats). Some smaller cars fall into this category, when they have the seat/luggage conversion built-in.

An 'estate car' is generally a version of a saloon/hatchback where the boot (trunk) continues at the maximum height of the car.

As for the luggage, no idea, I haven't owned a car since I moved to London, so it all gets rather hard to judge!