RE: City AT - yes, it really is that efficient. Of course, it feels something like a golf cart while accelerating...

Manual or Automatic? Having driven both, I'd say I still prefer the manual, even in traffic. If you've learned how to effectively "creep" in first or second gear, driving a manual in traffic isn't too bad. And it helps save your brakes from wear, lessens engine bay heat (from the torque converter sloshing through the ATF) and costs less to maintain.

Plus, it saves gas when you drive aggressively, too, no transmission lag or hesitation forcing you to put your foot to the floor, and no unnecessary upshifting or downshifting in other situations... of course, newer ATs and CVTs are much better, but I still prefer a stick. (Though I'd take a CVT for traffic driving any time)

RE: AT disposable? If you're driving a ten year old secondhand japanese car, with the budget of a person who would buy such car... the cost of overhauling is such that this is what most people do... they just swap in a surplus tranny. Much cheaper.