As far as vehicles crossing razor or concertina, IMHO if the vehicle is tracked, it goes straight through. This ability is why the tank was first used in WWI. To break through the masses of wires used by the German Army in the trench warfare. Once the wire was broken, the infantry could engage the enemy to clear out the trench. (A nice side note, tanks were impervious to machine gun fire. The infantry learned very quickly to get behind the tank to lessen casualties.) There is the small issue of noise. There is nothing that says "Good morning, sunshine" like the sound of heavy treads smashing into your defensive works. Hopefully, you have something nasty planned....
Now a wheeled vehicle? Like Paul said, I gots' to think about that....
My $0.02
Mike