K-Wagen super-heavy tank of 1918.
It was a real monster, thirteen metres long and carrying a crew of 26. It never made it into action, but it only just missed out when the war ended in November 1918.
It's available at http://shpws.me/MXQh. Unfortunately, being a big vehicle means that it's a big model with a big price. Alas, there's nothing much I can do about that except complain endlessly.