Initialize WheeledVehicleMovementComponent

AWheeledVehicle constructor:

FName AWheeledVehicle::VehicleMovementComponentName(TEXT("MovementComp"));
    
FName AWheeledVehicle::VehicleMeshComponentName(TEXT("VehicleMesh"));
    
AWheeledVehicle::AWheeledVehicle(const FObjectInitializer& ObjectInitializer) : Super(ObjectInitializer)
{
  Mesh = ObjectInitializer.CreateDefaultSubobject<USkeletalMeshComponent>(this, VehicleMeshComponentName);
  Mesh->SetCollisionProfileName(UCollisionProfile::Vehicle_ProfileName);
  Mesh->BodyInstance.bSimulatePhysics = true;
  Mesh->BodyInstance.bNotifyRigidBodyCollision = true;
  Mesh->BodyInstance.bUseCCD = true;
  Mesh->bBlendPhysics = true;
  Mesh->bGenerateOverlapEvents = true;
  Mesh->bCanEverAffectNavigation = false;
  RootComponent = Mesh;

  VehicleMovement = ObjectInitializer.CreateDefaultSubobject<UWheeledVehicleMovementComponent, UWheeledVehicleMovementComponent4W>(this, VehicleMovementComponentName);
  VehicleMovement->SetIsReplicated(true); // Enable replication by default
  VehicleMovement->UpdatedComponent = Mesh;
}

UWheeledVehicleMovementComponent4W declaration:

UCLASS()
class ENGINE_API UWheeledVehicleMovementComponent4W : public UWheeledVehicleMovementComponent

There are a lot of code inside UWheeledVehicleMovementComponent4W. You can download all this files from GitHub.