Looking pretty good, some nice details on the top view but I think It still has that rectangle shape showing through.
As Inferno pointed out, the six engines seem a bit excessive, perhaps drop the two outermost then slight spread and resize the remaining four to cover the gaps. Maybe push middle two engines more prominent from the covering oval to ease the shape?
The underside is on the money, especially the hydrolic rams reinforcing the front, very mad max. The only area that might need altering is the two armour blocks in the middle though the only idea that strikes me is a raising the entire section to the high of the armour with a set of cargobay doors sunk into the center.
The front is bad ass, no two ways about it. It's got spikes, its got menace and it has a battering ram. You could push the nose forward a little to make the front look like a cowcatcher (the half pyramid thing on the front of trains) but I don't know if that'd ruin the lines.
