I'm not sure that bringing actual tanks to E3 qualifies as the most outlandish E3 stunt ever but it's pretty far on the list. The folks at Wargaming.net are bringing three World War II tanks to the event next week to promote World of Tanks
next week and have released this video of their Hetzer tank destroyer being loaded up and delivered to the LA Convention center.
During the show they'll be bringing in an American M4A3 Sherman (Sunday at 12:15)and a Russian T35/85 (Monday at 3:30). Worth checking out if you're a tank nerd.