diff --git a/selfdrive/car/interfaces.py b/selfdrive/car/interfaces.py
index 3d4bf543e0..ecb059b728 100644
--- a/selfdrive/car/interfaces.py
+++ b/selfdrive/car/interfaces.py
@@ -103,7 +103,7 @@ class CarInterfaceBase(ABC):
     self.cp_adas = self.CS.get_adas_can_parser(CP)
     self.cp_body = self.CS.get_body_can_parser(CP)
     self.cp_loopback = self.CS.get_loopback_can_parser(CP)
-    self.can_parsers = [self.cp, self.cp_cam, self.cp_adas, self.cp_body, self.cp_loopback]
+    self.can_parsers = (self.cp, self.cp_cam, self.cp_adas, self.cp_body, self.cp_loopback)
 
     dbc_name = "" if self.cp is None else self.cp.dbc_name
     self.CC: CarControllerBase = CarController(dbc_name, CP)
@@ -246,17 +246,15 @@ class CarInterfaceBase(ABC):
       self.v_ego_cluster_seen = True
 
     # Many cars apply hysteresis to the ego dash speed
-    if self.CS is not None:
-      ret.vEgoCluster = apply_hysteresis(ret.vEgoCluster, self.CS.out.vEgoCluster, self.CS.cluster_speed_hyst_gap)
-      if abs(ret.vEgo) < self.CS.cluster_min_speed:
-        ret.vEgoCluster = 0.0
+    ret.vEgoCluster = apply_hysteresis(ret.vEgoCluster, self.CS.out.vEgoCluster, self.CS.cluster_speed_hyst_gap)
+    if abs(ret.vEgo) < self.CS.cluster_min_speed:
+      ret.vEgoCluster = 0.0
 
     if ret.cruiseState.speedCluster == 0:
       ret.cruiseState.speedCluster = ret.cruiseState.speed
 
     # copy back for next iteration
-    if self.CS is not None:
-      self.CS.out = ret.as_reader()
+    self.CS.out = ret.as_reader()
 
     return ret
 
diff --git a/selfdrive/car/tests/test_car_interfaces.py b/selfdrive/car/tests/test_car_interfaces.py
index 9e3c7d157e..107c13a14b 100644
--- a/selfdrive/car/tests/test_car_interfaces.py
+++ b/selfdrive/car/tests/test_car_interfaces.py
@@ -11,6 +11,7 @@ from openpilot.selfdrive.car.car_helpers import interfaces
 from openpilot.selfdrive.car.fingerprints import all_known_cars
 from openpilot.selfdrive.car.fw_versions import FW_VERSIONS, FW_QUERY_CONFIGS
 from openpilot.selfdrive.car.interfaces import get_interface_attr
+from openpilot.selfdrive.car.mock.values import CAR as MOCK
 from openpilot.selfdrive.controls.lib.latcontrol_angle import LatControlAngle
 from openpilot.selfdrive.controls.lib.latcontrol_pid import LatControlPID
 from openpilot.selfdrive.controls.lib.latcontrol_torque import LatControlTorque
@@ -51,7 +52,7 @@ def get_fuzzy_car_interface_args(draw: DrawType) -> dict:
 class TestCarInterfaces:
   # FIXME: Due to the lists used in carParams, Phase.target is very slow and will cause
   #  many generated examples to overrun when max_examples > ~20, don't use it
-  @parameterized.expand([(car,) for car in sorted(all_known_cars())])
+  @parameterized.expand([(car,) for car in sorted(all_known_cars())] + [MOCK.MOCK])
   @settings(max_examples=MAX_EXAMPLES, deadline=None,
             phases=(Phase.reuse, Phase.generate, Phase.shrink))
   @given(data=st.data())
@@ -81,9 +82,10 @@ class TestCarInterfaces:
     if car_params.steerControlType != car.CarParams.SteerControlType.angle:
       tune = car_params.lateralTuning
       if tune.which() == 'pid':
-        assert not math.isnan(tune.pid.kf) and tune.pid.kf > 0
-        assert len(tune.pid.kpV) > 0 and len(tune.pid.kpV) == len(tune.pid.kpBP)
-        assert len(tune.pid.kiV) > 0 and len(tune.pid.kiV) == len(tune.pid.kiBP)
+        if car_name != MOCK.MOCK:
+          assert not math.isnan(tune.pid.kf) and tune.pid.kf > 0
+          assert len(tune.pid.kpV) > 0 and len(tune.pid.kpV) == len(tune.pid.kpBP)
+          assert len(tune.pid.kiV) > 0 and len(tune.pid.kiV) == len(tune.pid.kiBP)
 
       elif tune.which() == 'torque':
         assert not math.isnan(tune.torque.kf) and tune.torque.kf > 0