Reply to Uzi4u
When did I ever claim that the M1A2 Abrams was a deployable main battle tank? You need either a beach landing or a fully established airfield to move the things in theatre!
The M1 Abrams was designed for essentially the same purpose as the Merkava. Defensive actions out of established bases, in the case of the Abrams, bases in Western Europe.
ALL modern main battle tanks have incredibly poor mobility and deployability, it's just not that apparent because the only thing natural to compare them to are... other main battle tanks designed around the same outdated strategic purposes. Tank designers don't even think about what the tank is going to be used for nowadays, they just compare it to the M1 Abrams or the Leopard 2.
There's no doubt that the sweeping armored thrusts that the Abrams performed in both Gulf wars were incredibly effective, but compared to a vehicle designed specifically for the purpose of high-mobility armored warfare (a vehicle that doesn't exist in the modern world!), the performance would be found to be poor in comparison.
I'd stop trying to build tanks that are both the ultimate street-fighting tank and the ultimate tank vs tank vehicle (such as the Merkava undoubtedly is, combat-wise), at the expense of actual strategic usefulness.
For a tank-vs-tank vehicle, I'd sacrifice armor protection (because let's face it, as it is there isn't a tank armor out there that can't be penetrated by /some/ form of attack, not even the Merkava's) for a more powerful main gun, and naturally have a lighter weight, better mobility, and lower cost. It'll level the playing field combat-wise. A single shot from a Merkava's ultra-powerful 120mm gun would knock one out, but put a gun big enough that a single shot can knock a Merkava out too... sounds even to me.
For urban fighting, that ultra-powerful 120mm gun is OVERPOWERED. You don't need that much penetration to blast an improvised bunker, or strong point. A lighter weapon such as a 76mm with a load of both low-trajectory high velocity rounds, and high-trajectory mortar-type rounds (eliminates the need for a seperate 60mm mortar like in the Merkava) would be effective enough. A smaller engine would also keep the weight lower to facilitate more effective transport in-theatre, as high vehicle top-speed isn't as critical when commited to clearing an urban area of enemies.