A West German light tank destroyer prototype armed with a 90mm cannon, developed in the 1950s. It was designed to be small, mobile, and air-droppable, allowing them to easily ambush mass Soviet armoured attacks.
It’s available in World of Tanks and World of Tanks Blitz as a Tier 7 light tank, notable for poor armour but great mobility and stealth.
I know World War 2 prototypes are cool, b it have you heard of the Spahpanzer SP.I C?