a truck against Ironman? Thats the best you can think of? Even if he doesnt destroy it before it hits him, i think that the suit has withstood worst than that.
Magneto would destroy Iron Man. Magneto would rip Iron Man in half with the snap of his fingers.
Even if Iron Man used an impermeable suit, Magneto could stop anything Iron Man tries to dish out simply by use his magnetic force fields.
If Magneto couldn't control Iron Man's armor, he'd use his mind to lift the nearest 40 ton 18 wheeler and demolish him with it.
But on the other hand, not even Magneto could defeat Doom. The Doc is the ultimate bad guy.