Willys is one of the scrapped or not finished Vehicles not-featured in the game. It only can be seen on a promotional image. As with everything else not made in the final version, the vehicle lacks a skill image.
One possible reason of being cut-out could be lack of resources allocated needed to fabricate another entity, as Willys holds two Troopers, while any other vehicle represent a single trooper, showing his stats sheet on left-click (except Fighter Jet). Even more, Willys essentially doesn't need a driver, as the gunner would suffice to consider it manned. The second trooper is just present cosmetically, suffering the same Fall Damage upon destruction not being of any use. Could be more trouble than worth.
On top of that, it's not really clear why the vehicle was included in promotional material. Either developers have got plans to finish it, or just want to tease the players.
- It's not the only early XX century materiel seen in the game, which could probably mean than one of initial concepts was placed in a corresponding era hence some of the stylistic elements, but then revoked in favour of Modern one, giving a strange feeling visual mix.