@ evil spike. Yes it is the new king tiger. It is mounted with a heschel turret and looks as if it is in for quit a fight.
IS3 doesn't take fuel because it is an off-map unit. Like others, it has an inflated MP cost to make up for no fuel cost. It costs 800MP to call in.
Seriously, the thing is beastial.
Haven't tested it yet. However, the 800MP is an upfront cost compared to the KT upfront +MP reduction. Upfront costs are more difficult to achieve. I believe the KT would probably beat the IS3. However, the IS3 can gain vet which would flip the balance around again. Seriously, the thing is beastial.