[Shryke]

There may be some space to be saved in fuel, engine, and systems requirements for an "urban" tank. We certainly don't need a 60mph-over-rough-terrain vehicle. Nor do we need many of the higly-advanced fighting systems (such as the gun-steadying mechanisms). Basically, we need a heavily armored, short-cannoned (fletchette rounds?) fighting vehicle, with moderate speed needs and moderate range. That may shave some space off, a decent amount, but we still would need.....I'd hazard 3 guys, as the "main" gun loader would not be a priority task (if it was, just use a MBT to level the damn town). Feel free to change or add.

[r9etb]

As this story also makes clear, you do need something capable of operating through/over rubble, barricades, and other vehicles. (A pointy nose, and/or some sort of snowplow-like blade would do the trick.) That suggests the need for a powerful engine.

I think you probably also need a very short turning radius, which probably means a tracked, as opposed to wheeled vehicle.

Also, you probably need to mount several guns (probably remote-controlled) to provide simultaneous firing in more than one direction.

And, of course, you need to have something that provides really good visibility.

[Centurion2000]

If you are looking at smth for urban combat .... two or three reloadable cannisters/tubes of 40mm flechette rounds; it should stand up to an RPG-7 at minimum, 50km/hr and a rotary 20mm main gun plus associated coax and driver's weapons would do quite well.

[FastCoyote]

It looks like it has to be something big enough to blow through a road block. Maybe not M1 size, but I don't think a Stryker can push aside, or go over, a burning car for example.