The physics asset body was missing PhysicsType. BuildPhysicsAsset created the
USkeletalBodySetup with a box but never set Body->PhysicsType, leaving it
PhysType_Default ('follow owner'). The base AWheeledVehiclePawn sets
Mesh->BodyInstance.bSimulatePhysics=false (the Chaos async solver drives it), so
'follow owner' meant the chassis never simulated - the vehicle sat frozen at
spawn (simulating=0) and -drivetest reported speed=0 travelled=0.
Set Body->PhysicsType = EPhysicsType::PhysType_Simulated. Result: simulating=1,
settled at Z 77 cm, and the drive test moves the car (36.3 m). It drives backwards
(-96.5 km/h) - the next bug is the reverse direction, not the physics setup.
zwitschi
927e9376a8