diff --git a/selfdrive/car/data_structures.py b/selfdrive/car/data_structures.py
index 4417466227..ef443907a7 100644
--- a/selfdrive/car/data_structures.py
+++ b/selfdrive/car/data_structures.py
@@ -100,7 +100,24 @@ class CarParams:
 
   longitudinalTuning: 'CarParams.LongitudinalPIDTuning' = field(default_factory=lambda: CarParams.LongitudinalPIDTuning())
   lateralParams: 'CarParams.LateralParams' = field(default_factory=lambda: CarParams.LateralParams())
-  lateralTuning: 'CarParams.LateralPIDTuning | CarParams.LateralTorqueTuning' = field(default_factory=lambda: CarParams.LateralPIDTuning())
+  # lateralTuning: 'CarParams.LateralPIDTuning | CarParams.LateralTorqueTuning' = field(default_factory=lambda: CarParams.LateralPIDTuning())
+  # lateralTuningWhich: type['CarParams.LateralPIDTuning | CarParams.LateralTorqueTuning'] = field(default_factory=lambda: CarParams.LateralPIDTuning)
+  # lateralPIDTuning: 'CarParams.LateralPIDTuning' = field(default_factory=lambda: CarParams.LateralPIDTuning())
+  # lateralTorqueTuning: 'CarParams.LateralTorqueTuning' = field(default_factory=lambda: CarParams.LateralTorqueTuning())
+
+  lateralTuning: 'CarParams.LateralTuning' = field(default_factory=lambda: CarParams.LateralTuning())
+
+  @dataclass
+  @apply_auto_fields
+  class LateralTuning:
+    def init(self, which: str):
+      assert which in ('pid', 'torque'), 'Invalid union type'
+      self.which = which
+
+    which: str = 'pid'
+
+    pid: 'CarParams.LateralPIDTuning' = field(default_factory=lambda: CarParams.LateralPIDTuning())
+    torque: 'CarParams.LateralTorqueTuning' = field(default_factory=lambda: CarParams.LateralTorqueTuning())
 
   @dataclass
   @apply_auto_fields
@@ -215,3 +232,60 @@ class CarParams:
     programmedFuelInjection = auto()
 
     debug = auto()
+
+
+import typing
+
+# CP = CarParams()
+#
+# print(CP.lateralTuningWhich is CarParams.LateralPIDTuning)
+# print(CP.lateralTuningWhich is CarParams.LateralTorqueTuning)
+# print()
+# CP.lateralTuningWhich = CarParams.LateralTorqueTuning
+# print(CP.lateralTuningWhich is CarParams.LateralPIDTuning)
+# print(CP.lateralTuningWhich is CarParams.LateralTorqueTuning)
+
+#
+#
+# T = typing.TypeVar('T')
+#
+# @dataclass
+# class UnionField(typing.Generic[T]):
+#     value: T
+#
+#     def init(self, value: T):
+#         self.value = value
+#
+#     def which(self):
+#         return type(self.value).__name__
+#
+#
+# lateral_tuning: UnionField[CarParams.LateralTorqueTuning | CarParams.LateralPIDTuning] = UnionField(CarParams.LateralPIDTuning)
+#
+# lateral_tuning.init(CarParams().LateralPIDTuning())
+# if isinstance(lateral_tuning.value, CarParams.LateralTorqueTuning):
+#   print(lateral_tuning.value.useSteeringAngle)  # This will work without mypy errors
+
+T = typing.TypeVar('T')
+
+
+# def which(value: object, typ: typing.Type[T]) -> bool:
+#   return isinstance(value, typ)
+
+which = isinstance
+
+
+lateralTuning: CarParams.LateralPIDTuning | CarParams.LateralTorqueTuning = field(default_factory=lambda: CarParams.LateralPIDTuning())
+
+if isinstance(lateralTuning, CarParams.LateralTorqueTuning):
+  lateralTuning.useSteeringAngle = True
+
+
+
+# @dataclass
+# @apply_auto_fields
+# class UnionDataclass:
+#   which: str = 'pid'
+#
+#   pid: CarParams.LateralPIDTuning = auto_field()
+#   torque: CarParams.LateralTorqueTuning = auto_field()
diff --git a/selfdrive/car/interfaces.py b/selfdrive/car/interfaces.py
index 4b56b26469..53d5100a4f 100644
--- a/selfdrive/car/interfaces.py
+++ b/selfdrive/car/interfaces.py
@@ -189,7 +189,6 @@ class CarInterfaceBase(ABC):
     # standard ALC params
     ret.tireStiffnessFactor = 1.0
     ret.steerControlType = CarParams.SteerControlType.torque
-    ret.lateralParams = CarParams.LateralPIDTuning()
     ret.minSteerSpeed = 0.
     ret.wheelSpeedFactor = 1.0