diff --git a/selfdrive/car/body/interface.py b/selfdrive/car/body/interface.py
index ae7ab89aab..638134be7f 100644
--- a/selfdrive/car/body/interface.py
+++ b/selfdrive/car/body/interface.py
@@ -2,16 +2,13 @@
 import math
 from cereal import car
 from common.realtime import DT_CTRL
-from selfdrive.car import scale_rot_inertia, scale_tire_stiffness, get_safety_config
+from selfdrive.car import scale_tire_stiffness, get_safety_config
 from selfdrive.car.interfaces import CarInterfaceBase
 from selfdrive.car.body.values import SPEED_FROM_RPM
 
 class CarInterface(CarInterfaceBase):
   @staticmethod
-  def get_params(candidate, fingerprint=None, car_fw=None, experimental_long=False):
-
-    ret = CarInterfaceBase.get_std_params(candidate, fingerprint)
-
+  def _get_params(ret, candidate, fingerprint, car_fw, experimental_long):
     ret.notCar = True
     ret.carName = "body"
     ret.safetyConfigs = [get_safety_config(car.CarParams.SafetyModel.body)]
@@ -31,8 +28,6 @@ class CarInterface(CarInterfaceBase):
     ret.openpilotLongitudinalControl = True
     ret.steerControlType = car.CarParams.SteerControlType.angle
 
-    ret.rotationalInertia = scale_rot_inertia(ret.mass, ret.wheelbase)
-
     ret.tireStiffnessFront, ret.tireStiffnessRear = scale_tire_stiffness(ret.mass, ret.wheelbase, ret.centerToFront)
 
     return ret
diff --git a/selfdrive/car/chrysler/interface.py b/selfdrive/car/chrysler/interface.py
index 245e10650c..9b5e5a5ce5 100755
--- a/selfdrive/car/chrysler/interface.py
+++ b/selfdrive/car/chrysler/interface.py
@@ -1,21 +1,18 @@
 #!/usr/bin/env python3
 from cereal import car
 from panda import Panda
-from selfdrive.car import STD_CARGO_KG, scale_rot_inertia, scale_tire_stiffness, gen_empty_fingerprint, get_safety_config
+from selfdrive.car import STD_CARGO_KG, scale_tire_stiffness, get_safety_config
 from selfdrive.car.chrysler.values import CAR, DBC, RAM_HD, RAM_DT
 from selfdrive.car.interfaces import CarInterfaceBase
 
 
 class CarInterface(CarInterfaceBase):
   @staticmethod
-  def get_params(candidate, fingerprint=gen_empty_fingerprint(), car_fw=None, experimental_long=False):
-    ret = CarInterfaceBase.get_std_params(candidate, fingerprint)
+  def _get_params(ret, candidate, fingerprint, car_fw, experimental_long):
     ret.carName = "chrysler"
-
     ret.dashcamOnly = candidate in RAM_HD
 
     ret.radarOffCan = DBC[candidate]['radar'] is None
-
     ret.steerActuatorDelay = 0.1
     ret.steerLimitTimer = 0.4
 
@@ -76,9 +73,6 @@ class CarInterface(CarInterfaceBase):
 
     ret.centerToFront = ret.wheelbase * 0.44
 
-    # starting with reasonable value for civic and scaling by mass and wheelbase
-    ret.rotationalInertia = scale_rot_inertia(ret.mass, ret.wheelbase)
-
     # TODO: start from empirically derived lateral slip stiffness for the civic and scale by
     # mass and CG position, so all cars will have approximately similar dyn behaviors
     ret.tireStiffnessFront, ret.tireStiffnessRear = scale_tire_stiffness(ret.mass, ret.wheelbase, ret.centerToFront)
diff --git a/selfdrive/car/ford/interface.py b/selfdrive/car/ford/interface.py
index 4943db076f..913c3c926d 100644
--- a/selfdrive/car/ford/interface.py
+++ b/selfdrive/car/ford/interface.py
@@ -1,7 +1,7 @@
 #!/usr/bin/env python3
 from cereal import car
 from common.conversions import Conversions as CV
-from selfdrive.car import STD_CARGO_KG, scale_rot_inertia, scale_tire_stiffness, gen_empty_fingerprint, get_safety_config
+from selfdrive.car import STD_CARGO_KG, scale_tire_stiffness, get_safety_config
 from selfdrive.car.ford.values import CAR, Ecu, TransmissionType, GearShifter
 from selfdrive.car.interfaces import CarInterfaceBase
 
@@ -10,12 +10,7 @@ CarParams = car.CarParams
 
 class CarInterface(CarInterfaceBase):
   @staticmethod
-  def get_params(candidate, fingerprint=gen_empty_fingerprint(), car_fw=None, experimental_long=False):
-    if car_fw is None:
-      car_fw = []
-
-    ret = CarInterfaceBase.get_std_params(candidate, fingerprint)
-
+  def _get_params(ret, candidate, fingerprint, car_fw, experimental_long):
     ret.carName = "ford"
     ret.dashcamOnly = True
     ret.safetyConfigs = [get_safety_config(CarParams.SafetyModel.ford)]
@@ -24,7 +19,6 @@ class CarInterface(CarInterfaceBase):
     ret.steerControlType = CarParams.SteerControlType.angle
     ret.steerActuatorDelay = 0.4
     ret.steerLimitTimer = 1.0
-    tire_stiffness_factor = 1.0
 
     if candidate == CAR.ESCAPE_MK4:
       ret.wheelbase = 2.71
@@ -60,10 +54,8 @@ class CarInterface(CarInterfaceBase):
     ret.minSteerSpeed = 0.
 
     ret.autoResumeSng = ret.minEnableSpeed == -1.
-    ret.rotationalInertia = scale_rot_inertia(ret.mass, ret.wheelbase)
     ret.centerToFront = ret.wheelbase * 0.44
-    ret.tireStiffnessFront, ret.tireStiffnessRear = scale_tire_stiffness(ret.mass, ret.wheelbase, ret.centerToFront,
-                                                                         tire_stiffness_factor=tire_stiffness_factor)
+    ret.tireStiffnessFront, ret.tireStiffnessRear = scale_tire_stiffness(ret.mass, ret.wheelbase, ret.centerToFront)
     return ret
 
   def _update(self, c):
diff --git a/selfdrive/car/gm/interface.py b/selfdrive/car/gm/interface.py
index eb5ab7329a..7d38c60900 100755
--- a/selfdrive/car/gm/interface.py
+++ b/selfdrive/car/gm/interface.py
@@ -4,7 +4,7 @@ from math import fabs
 from panda import Panda
 
 from common.conversions import Conversions as CV
-from selfdrive.car import STD_CARGO_KG, create_button_event, scale_rot_inertia, scale_tire_stiffness, gen_empty_fingerprint, get_safety_config
+from selfdrive.car import STD_CARGO_KG, create_button_event, scale_tire_stiffness, get_safety_config
 from selfdrive.car.gm.values import CAR, CruiseButtons, CarControllerParams, EV_CAR, CAMERA_ACC_CAR
 from selfdrive.car.interfaces import CarInterfaceBase
 
@@ -44,8 +44,7 @@ class CarInterface(CarInterfaceBase):
       return CarInterfaceBase.get_steer_feedforward_default
 
   @staticmethod
-  def get_params(candidate, fingerprint=gen_empty_fingerprint(), car_fw=None, experimental_long=False):
-    ret = CarInterfaceBase.get_std_params(candidate, fingerprint)
+  def _get_params(ret, candidate, fingerprint, car_fw, experimental_long):
     ret.carName = "gm"
     ret.safetyConfigs = [get_safety_config(car.CarParams.SafetyModel.gm)]
     ret.autoResumeSng = False
@@ -195,10 +194,6 @@ class CarInterface(CarInterfaceBase):
       ret.centerToFront = ret.wheelbase * 0.4
       CarInterfaceBase.configure_torque_tune(candidate, ret.lateralTuning)
 
-    # TODO: get actual value, for now starting with reasonable value for
-    # civic and scaling by mass and wheelbase
-    ret.rotationalInertia = scale_rot_inertia(ret.mass, ret.wheelbase)
-
     # TODO: start from empirically derived lateral slip stiffness for the civic and scale by
     # mass and CG position, so all cars will have approximately similar dyn behaviors
     ret.tireStiffnessFront, ret.tireStiffnessRear = scale_tire_stiffness(ret.mass, ret.wheelbase, ret.centerToFront,
diff --git a/selfdrive/car/honda/interface.py b/selfdrive/car/honda/interface.py
index e397f02838..990238ae5d 100755
--- a/selfdrive/car/honda/interface.py
+++ b/selfdrive/car/honda/interface.py
@@ -4,7 +4,7 @@ from panda import Panda
 from common.conversions import Conversions as CV
 from common.numpy_fast import interp
 from selfdrive.car.honda.values import CarControllerParams, CruiseButtons, HondaFlags, CAR, HONDA_BOSCH, HONDA_NIDEC_ALT_SCM_MESSAGES, HONDA_BOSCH_ALT_BRAKE_SIGNAL, HONDA_BOSCH_RADARLESS
-from selfdrive.car import STD_CARGO_KG, CivicParams, create_button_event, scale_rot_inertia, scale_tire_stiffness, gen_empty_fingerprint, get_safety_config
+from selfdrive.car import STD_CARGO_KG, CivicParams, create_button_event, scale_tire_stiffness, get_safety_config
 from selfdrive.car.interfaces import CarInterfaceBase
 from selfdrive.car.disable_ecu import disable_ecu
 
@@ -29,8 +29,7 @@ class CarInterface(CarInterfaceBase):
       return CarControllerParams.NIDEC_ACCEL_MIN, interp(current_speed, ACCEL_MAX_BP, ACCEL_MAX_VALS)
 
   @staticmethod
-  def get_params(candidate, fingerprint=gen_empty_fingerprint(), car_fw=[], experimental_long=False):  # pylint: disable=dangerous-default-value
-    ret = CarInterfaceBase.get_std_params(candidate, fingerprint)
+  def _get_params(ret, candidate, fingerprint, car_fw, experimental_long):
     ret.carName = "honda"
 
     if candidate in HONDA_BOSCH:
@@ -291,10 +290,6 @@ class CarInterface(CarInterfaceBase):
     stop_and_go = candidate in (HONDA_BOSCH | {CAR.CIVIC}) or ret.enableGasInterceptor
     ret.minEnableSpeed = -1. if stop_and_go else 25.5 * CV.MPH_TO_MS
 
-    # TODO: get actual value, for now starting with reasonable value for
-    # civic and scaling by mass and wheelbase
-    ret.rotationalInertia = scale_rot_inertia(ret.mass, ret.wheelbase)
-
     # TODO: start from empirically derived lateral slip stiffness for the civic and scale by
     # mass and CG position, so all cars will have approximately similar dyn behaviors
     ret.tireStiffnessFront, ret.tireStiffnessRear = scale_tire_stiffness(ret.mass, ret.wheelbase, ret.centerToFront,
diff --git a/selfdrive/car/hyundai/interface.py b/selfdrive/car/hyundai/interface.py
index 3ecf5289ff..c1fe8be4c2 100644
--- a/selfdrive/car/hyundai/interface.py
+++ b/selfdrive/car/hyundai/interface.py
@@ -4,7 +4,7 @@ from panda import Panda
 from common.conversions import Conversions as CV
 from selfdrive.car.hyundai.values import HyundaiFlags, CAR, DBC, CANFD_CAR, CAMERA_SCC_CAR, CANFD_RADAR_SCC_CAR, EV_CAR, HYBRID_CAR, LEGACY_SAFETY_MODE_CAR, Buttons
 from selfdrive.car.hyundai.radar_interface import RADAR_START_ADDR
-from selfdrive.car import STD_CARGO_KG, create_button_event, scale_rot_inertia, scale_tire_stiffness, gen_empty_fingerprint, get_safety_config
+from selfdrive.car import STD_CARGO_KG, create_button_event, scale_tire_stiffness, get_safety_config
 from selfdrive.car.interfaces import CarInterfaceBase
 from selfdrive.car.disable_ecu import disable_ecu
 
@@ -18,9 +18,7 @@ BUTTONS_DICT = {Buttons.RES_ACCEL: ButtonType.accelCruise, Buttons.SET_DECEL: Bu
 
 class CarInterface(CarInterfaceBase):
   @staticmethod
-  def get_params(candidate, fingerprint=gen_empty_fingerprint(), car_fw=[], experimental_long=False):  # pylint: disable=dangerous-default-value
-    ret = CarInterfaceBase.get_std_params(candidate, fingerprint)
-
+  def _get_params(ret, candidate, fingerprint, car_fw, experimental_long):
     ret.carName = "hyundai"
     ret.radarOffCan = RADAR_START_ADDR not in fingerprint[1] or DBC[ret.carFingerprint]["radar"] is None
 
@@ -267,10 +265,6 @@ class CarInterface(CarInterfaceBase):
 
     ret.centerToFront = ret.wheelbase * 0.4
 
-    # TODO: get actual value, for now starting with reasonable value for
-    # civic and scaling by mass and wheelbase
-    ret.rotationalInertia = scale_rot_inertia(ret.mass, ret.wheelbase)
-
     # TODO: start from empirically derived lateral slip stiffness for the civic and scale by
     # mass and CG position, so all cars will have approximately similar dyn behaviors
     ret.tireStiffnessFront, ret.tireStiffnessRear = scale_tire_stiffness(ret.mass, ret.wheelbase, ret.centerToFront,
diff --git a/selfdrive/car/interfaces.py b/selfdrive/car/interfaces.py
index 820e429cc4..e03f1cfada 100644
--- a/selfdrive/car/interfaces.py
+++ b/selfdrive/car/interfaces.py
@@ -10,7 +10,7 @@ from common.conversions import Conversions as CV
 from common.kalman.simple_kalman import KF1D
 from common.numpy_fast import interp
 from common.realtime import DT_CTRL
-from selfdrive.car import apply_hysteresis, gen_empty_fingerprint
+from selfdrive.car import apply_hysteresis, gen_empty_fingerprint, scale_rot_inertia
 from selfdrive.controls.lib.drive_helpers import V_CRUISE_MAX, apply_slack
 from selfdrive.controls.lib.events import Events
 from selfdrive.controls.lib.vehicle_model import VehicleModel
@@ -87,10 +87,28 @@ class CarInterfaceBase(ABC):
   def get_pid_accel_limits(CP, current_speed, cruise_speed):
     return ACCEL_MIN, ACCEL_MAX
 
+  @classmethod
+  def get_params(cls, candidate: str, fingerprint: Optional[Dict[int, Dict[int, int]]] = None, car_fw: Optional[List[car.CarParams.CarFw]] = None, experimental_long: bool = False):
+    if fingerprint is None:
+      fingerprint = gen_empty_fingerprint()
+
+    if car_fw is None:
+      car_fw = list()
+
+    ret = CarInterfaceBase.get_std_params(candidate)
+    ret = cls._get_params(ret, candidate, fingerprint, car_fw, experimental_long)
+
+    # Set common params using fields set by the car interface
+    # TODO: get actual value, for now starting with reasonable value for
+    # civic and scaling by mass and wheelbase
+    ret.rotationalInertia = scale_rot_inertia(ret.mass, ret.wheelbase)
+
+    return ret
+
   @staticmethod
   @abstractmethod
-  def get_params(candidate, fingerprint=gen_empty_fingerprint(), car_fw=None, experimental_long=False):
-    pass
+  def _get_params(ret: car.CarParams, candidate: str, fingerprint: Dict[int, Dict[int, int]], car_fw: List[car.CarParams.CarFw], experimental_long: bool):
+    raise NotImplementedError
 
   @staticmethod
   def init(CP, logcan, sendcan):
@@ -121,7 +139,7 @@ class CarInterfaceBase(ABC):
 
   # returns a set of default params to avoid repetition in car specific params
   @staticmethod
-  def get_std_params(candidate, fingerprint):
+  def get_std_params(candidate):
     ret = car.CarParams.new_message()
     ret.carFingerprint = candidate
 
diff --git a/selfdrive/car/mazda/interface.py b/selfdrive/car/mazda/interface.py
index 7c42431e33..fdd2439ff9 100755
--- a/selfdrive/car/mazda/interface.py
+++ b/selfdrive/car/mazda/interface.py
@@ -2,7 +2,7 @@
 from cereal import car
 from common.conversions import Conversions as CV
 from selfdrive.car.mazda.values import CAR, LKAS_LIMITS
-from selfdrive.car import STD_CARGO_KG, scale_rot_inertia, scale_tire_stiffness, gen_empty_fingerprint, get_safety_config
+from selfdrive.car import STD_CARGO_KG, scale_tire_stiffness, get_safety_config
 from selfdrive.car.interfaces import CarInterfaceBase
 
 ButtonType = car.CarState.ButtonEvent.Type
@@ -11,9 +11,7 @@ EventName = car.CarEvent.EventName
 class CarInterface(CarInterfaceBase):
 
   @staticmethod
-  def get_params(candidate, fingerprint=gen_empty_fingerprint(), car_fw=None, experimental_long=False):
-    ret = CarInterfaceBase.get_std_params(candidate, fingerprint)
-
+  def _get_params(ret, candidate, fingerprint, car_fw, experimental_long):
     ret.carName = "mazda"
     ret.safetyConfigs = [get_safety_config(car.CarParams.SafetyModel.mazda)]
     ret.radarOffCan = True
@@ -48,10 +46,6 @@ class CarInterface(CarInterfaceBase):
 
     ret.centerToFront = ret.wheelbase * 0.41
 
-    # TODO: get actual value, for now starting with reasonable value for
-    # civic and scaling by mass and wheelbase
-    ret.rotationalInertia = scale_rot_inertia(ret.mass, ret.wheelbase)
-
     # TODO: start from empirically derived lateral slip stiffness for the civic and scale by
     # mass and CG position, so all cars will have approximately similar dyn behaviors
     ret.tireStiffnessFront, ret.tireStiffnessRear = scale_tire_stiffness(ret.mass, ret.wheelbase, ret.centerToFront,
diff --git a/selfdrive/car/mock/interface.py b/selfdrive/car/mock/interface.py
index 2be1bcb4a3..3ac487dbb7 100755
--- a/selfdrive/car/mock/interface.py
+++ b/selfdrive/car/mock/interface.py
@@ -2,7 +2,7 @@
 from cereal import car
 from system.swaglog import cloudlog
 import cereal.messaging as messaging
-from selfdrive.car import gen_empty_fingerprint, get_safety_config
+from selfdrive.car import get_safety_config
 from selfdrive.car.interfaces import CarInterfaceBase
 
 
@@ -19,12 +19,10 @@ class CarInterface(CarInterfaceBase):
     self.prev_speed = 0.
 
   @staticmethod
-  def get_params(candidate, fingerprint=gen_empty_fingerprint(), car_fw=None, experimental_long=False):
-    ret = CarInterfaceBase.get_std_params(candidate, fingerprint)
+  def _get_params(ret, candidate, fingerprint, car_fw, experimental_long):
     ret.carName = "mock"
     ret.safetyConfigs = [get_safety_config(car.CarParams.SafetyModel.noOutput)]
     ret.mass = 1700.
-    ret.rotationalInertia = 2500.
     ret.wheelbase = 2.70
     ret.centerToFront = ret.wheelbase * 0.5
     ret.steerRatio = 13.  # reasonable
diff --git a/selfdrive/car/nissan/interface.py b/selfdrive/car/nissan/interface.py
index e095ceb461..194d7f06ae 100644
--- a/selfdrive/car/nissan/interface.py
+++ b/selfdrive/car/nissan/interface.py
@@ -1,6 +1,6 @@
 #!/usr/bin/env python3
 from cereal import car
-from selfdrive.car import STD_CARGO_KG, scale_rot_inertia, scale_tire_stiffness, gen_empty_fingerprint, get_safety_config
+from selfdrive.car import STD_CARGO_KG, scale_tire_stiffness, get_safety_config
 from selfdrive.car.interfaces import CarInterfaceBase
 from selfdrive.car.nissan.values import CAR
 
@@ -8,9 +8,7 @@ from selfdrive.car.nissan.values import CAR
 class CarInterface(CarInterfaceBase):
 
   @staticmethod
-  def get_params(candidate, fingerprint=gen_empty_fingerprint(), car_fw=None, experimental_long=False):
-
-    ret = CarInterfaceBase.get_std_params(candidate, fingerprint)
+  def _get_params(ret, candidate, fingerprint, car_fw, experimental_long):
     ret.carName = "nissan"
     ret.safetyConfigs = [get_safety_config(car.CarParams.SafetyModel.nissan)]
     ret.autoResumeSng = False
@@ -38,10 +36,6 @@ class CarInterface(CarInterfaceBase):
     ret.steerControlType = car.CarParams.SteerControlType.angle
     ret.radarOffCan = True
 
-    # TODO: get actual value, for now starting with reasonable value for
-    # civic and scaling by mass and wheelbase
-    ret.rotationalInertia = scale_rot_inertia(ret.mass, ret.wheelbase)
-
     # TODO: start from empirically derived lateral slip stiffness for the civic and scale by
     # mass and CG position, so all cars will have approximately similar dyn behaviors
     ret.tireStiffnessFront, ret.tireStiffnessRear = scale_tire_stiffness(ret.mass, ret.wheelbase, ret.centerToFront)
diff --git a/selfdrive/car/subaru/interface.py b/selfdrive/car/subaru/interface.py
index a920c02534..7dba8eaf23 100644
--- a/selfdrive/car/subaru/interface.py
+++ b/selfdrive/car/subaru/interface.py
@@ -1,7 +1,7 @@
 #!/usr/bin/env python3
 from cereal import car
 from panda import Panda
-from selfdrive.car import STD_CARGO_KG, scale_rot_inertia, scale_tire_stiffness, gen_empty_fingerprint, get_safety_config
+from selfdrive.car import STD_CARGO_KG, scale_tire_stiffness, get_safety_config
 from selfdrive.car.interfaces import CarInterfaceBase
 from selfdrive.car.subaru.values import CAR, GLOBAL_GEN2, PREGLOBAL_CARS
 
@@ -9,9 +9,7 @@ from selfdrive.car.subaru.values import CAR, GLOBAL_GEN2, PREGLOBAL_CARS
 class CarInterface(CarInterfaceBase):
 
   @staticmethod
-  def get_params(candidate, fingerprint=gen_empty_fingerprint(), car_fw=None, experimental_long=False):
-    ret = CarInterfaceBase.get_std_params(candidate, fingerprint)
-
+  def _get_params(ret, candidate, fingerprint, car_fw, experimental_long):
     ret.carName = "subaru"
     ret.radarOffCan = True
     ret.dashcamOnly = candidate in PREGLOBAL_CARS
@@ -103,10 +101,6 @@ class CarInterface(CarInterfaceBase):
     else:
       raise ValueError(f"unknown car: {candidate}")
 
-    # TODO: get actual value, for now starting with reasonable value for
-    # civic and scaling by mass and wheelbase
-    ret.rotationalInertia = scale_rot_inertia(ret.mass, ret.wheelbase)
-
     # TODO: start from empirically derived lateral slip stiffness for the civic and scale by
     # mass and CG position, so all cars will have approximately similar dyn behaviors
     ret.tireStiffnessFront, ret.tireStiffnessRear = scale_tire_stiffness(ret.mass, ret.wheelbase, ret.centerToFront)
diff --git a/selfdrive/car/tesla/interface.py b/selfdrive/car/tesla/interface.py
index 2eb29efb41..6573f4e4d9 100755
--- a/selfdrive/car/tesla/interface.py
+++ b/selfdrive/car/tesla/interface.py
@@ -2,14 +2,13 @@
 from cereal import car
 from panda import Panda
 from selfdrive.car.tesla.values import CANBUS, CAR
-from selfdrive.car import STD_CARGO_KG, gen_empty_fingerprint, scale_rot_inertia, scale_tire_stiffness, get_safety_config
+from selfdrive.car import STD_CARGO_KG, scale_tire_stiffness, get_safety_config
 from selfdrive.car.interfaces import CarInterfaceBase
 
 
 class CarInterface(CarInterfaceBase):
   @staticmethod
-  def get_params(candidate, fingerprint=gen_empty_fingerprint(), car_fw=None, experimental_long=False):
-    ret = CarInterfaceBase.get_std_params(candidate, fingerprint)
+  def _get_params(ret, candidate, fingerprint, car_fw, experimental_long):
     ret.carName = "tesla"
 
     # There is no safe way to do steer blending with user torque,
@@ -51,7 +50,6 @@ class CarInterface(CarInterfaceBase):
     else:
       raise ValueError(f"Unsupported car: {candidate}")
 
-    ret.rotationalInertia = scale_rot_inertia(ret.mass, ret.wheelbase)
     ret.tireStiffnessFront, ret.tireStiffnessRear = scale_tire_stiffness(ret.mass, ret.wheelbase, ret.centerToFront)
 
     return ret
diff --git a/selfdrive/car/toyota/interface.py b/selfdrive/car/toyota/interface.py
index 7ee5ac0d0e..d3835d175b 100644
--- a/selfdrive/car/toyota/interface.py
+++ b/selfdrive/car/toyota/interface.py
@@ -3,7 +3,7 @@ from cereal import car
 from common.conversions import Conversions as CV
 from panda import Panda
 from selfdrive.car.toyota.values import Ecu, CAR, ToyotaFlags, TSS2_CAR, RADAR_ACC_CAR, NO_DSU_CAR, MIN_ACC_SPEED, EPS_SCALE, EV_HYBRID_CAR, UNSUPPORTED_DSU_CAR, CarControllerParams, NO_STOP_TIMER_CAR
-from selfdrive.car import STD_CARGO_KG, scale_rot_inertia, scale_tire_stiffness, gen_empty_fingerprint, get_safety_config
+from selfdrive.car import STD_CARGO_KG, scale_tire_stiffness, get_safety_config
 from selfdrive.car.interfaces import CarInterfaceBase
 
 EventName = car.CarEvent.EventName
@@ -15,9 +15,7 @@ class CarInterface(CarInterfaceBase):
     return CarControllerParams.ACCEL_MIN, CarControllerParams.ACCEL_MAX
 
   @staticmethod
-  def get_params(candidate, fingerprint=gen_empty_fingerprint(), car_fw=[], experimental_long=False):  # pylint: disable=dangerous-default-value
-    ret = CarInterfaceBase.get_std_params(candidate, fingerprint)
-
+  def _get_params(ret, candidate, fingerprint, car_fw, experimental_long):
     ret.carName = "toyota"
     ret.safetyConfigs = [get_safety_config(car.CarParams.SafetyModel.toyota)]
     ret.safetyConfigs[0].safetyParam = EPS_SCALE[candidate]
@@ -190,10 +188,6 @@ class CarInterface(CarInterfaceBase):
 
     ret.centerToFront = ret.wheelbase * 0.44
 
-    # TODO: get actual value, for now starting with reasonable value for
-    # civic and scaling by mass and wheelbase
-    ret.rotationalInertia = scale_rot_inertia(ret.mass, ret.wheelbase)
-
     # TODO: start from empirically derived lateral slip stiffness for the civic and scale by
     # mass and CG position, so all cars will have approximately similar dyn behaviors
     ret.tireStiffnessFront, ret.tireStiffnessRear = scale_tire_stiffness(ret.mass, ret.wheelbase, ret.centerToFront,
diff --git a/selfdrive/car/volkswagen/interface.py b/selfdrive/car/volkswagen/interface.py
index e0bb917960..997cdfcfc1 100644
--- a/selfdrive/car/volkswagen/interface.py
+++ b/selfdrive/car/volkswagen/interface.py
@@ -1,8 +1,7 @@
 from cereal import car
 from panda import Panda
 from common.conversions import Conversions as CV
-from selfdrive.car import STD_CARGO_KG, scale_rot_inertia, scale_tire_stiffness, \
-                          gen_empty_fingerprint, get_safety_config
+from selfdrive.car import STD_CARGO_KG, scale_tire_stiffness, get_safety_config
 from selfdrive.car.interfaces import CarInterfaceBase
 from selfdrive.car.volkswagen.values import CAR, PQ_CARS, CANBUS, NetworkLocation, TransmissionType, GearShifter
 
@@ -22,8 +21,7 @@ class CarInterface(CarInterfaceBase):
       self.cp_ext = self.cp_cam
 
   @staticmethod
-  def get_params(candidate, fingerprint=gen_empty_fingerprint(), car_fw=None, experimental_long=False):
-    ret = CarInterfaceBase.get_std_params(candidate, fingerprint)
+  def _get_params(ret, candidate, fingerprint, car_fw, experimental_long):
     ret.carName = "volkswagen"
     ret.radarOffCan = True
 
@@ -74,7 +72,6 @@ class CarInterface(CarInterfaceBase):
     ret.steerActuatorDelay = 0.1
     ret.steerLimitTimer = 0.4
     ret.steerRatio = 15.6  # Let the params learner figure this out
-    tire_stiffness_factor = 1.0  # Let the params learner figure this out
     ret.lateralTuning.pid.kpBP = [0.]
     ret.lateralTuning.pid.kiBP = [0.]
     ret.lateralTuning.pid.kf = 0.00006
@@ -213,10 +210,8 @@ class CarInterface(CarInterfaceBase):
       raise ValueError(f"unsupported car {candidate}")
 
     ret.autoResumeSng = ret.minEnableSpeed == -1
-    ret.rotationalInertia = scale_rot_inertia(ret.mass, ret.wheelbase)
     ret.centerToFront = ret.wheelbase * 0.45
-    ret.tireStiffnessFront, ret.tireStiffnessRear = scale_tire_stiffness(ret.mass, ret.wheelbase, ret.centerToFront,
-                                                                         tire_stiffness_factor=tire_stiffness_factor)
+    ret.tireStiffnessFront, ret.tireStiffnessRear = scale_tire_stiffness(ret.mass, ret.wheelbase, ret.centerToFront)
     return ret
 
   # returns a car.CarState