diff --git a/selfdrive/car/body/interface.py b/selfdrive/car/body/interface.py
index 6b5ff2b4a9..9d3e1ccab6 100644
--- a/selfdrive/car/body/interface.py
+++ b/selfdrive/car/body/interface.py
@@ -6,7 +6,7 @@ from openpilot.selfdrive.car.body.values import SPEED_FROM_RPM
 
 class CarInterface(CarInterfaceBase):
   @staticmethod
-  def _get_params(ret: structs.CarParams, candidate, fingerprint, car_fw, experimental_long, docs):
+  def _get_params(ret: structs.CarParams, candidate, fingerprint, car_fw, experimental_long, docs) -> structs.CarParams:
     ret.notCar = True
     ret.carName = "body"
     ret.safetyConfigs = [get_safety_config(structs.CarParams.SafetyModel.body)]
diff --git a/selfdrive/car/chrysler/interface.py b/selfdrive/car/chrysler/interface.py
index e038472163..9092e92313 100755
--- a/selfdrive/car/chrysler/interface.py
+++ b/selfdrive/car/chrysler/interface.py
@@ -7,7 +7,7 @@ from openpilot.selfdrive.car.interfaces import CarInterfaceBase
 
 class CarInterface(CarInterfaceBase):
   @staticmethod
-  def _get_params(ret: structs.CarParams, candidate, fingerprint, car_fw, experimental_long, docs):
+  def _get_params(ret: structs.CarParams, candidate, fingerprint, car_fw, experimental_long, docs) -> structs.CarParams:
     ret.carName = "chrysler"
     ret.dashcamOnly = candidate in RAM_HD
 
diff --git a/selfdrive/car/ford/interface.py b/selfdrive/car/ford/interface.py
index 89bd25a017..17f136b1be 100644
--- a/selfdrive/car/ford/interface.py
+++ b/selfdrive/car/ford/interface.py
@@ -10,7 +10,7 @@ TransmissionType = structs.CarParams.TransmissionType
 
 class CarInterface(CarInterfaceBase):
   @staticmethod
-  def _get_params(ret: structs.CarParams, candidate, fingerprint, car_fw, experimental_long, docs):
+  def _get_params(ret: structs.CarParams, candidate, fingerprint, car_fw, experimental_long, docs) -> structs.CarParams:
     ret.carName = "ford"
     ret.dashcamOnly = bool(ret.flags & FordFlags.CANFD)
 
diff --git a/selfdrive/car/gm/interface.py b/selfdrive/car/gm/interface.py
index f76e98cc37..4f47dbde2c 100755
--- a/selfdrive/car/gm/interface.py
+++ b/selfdrive/car/gm/interface.py
@@ -80,7 +80,7 @@ class CarInterface(CarInterfaceBase):
       return self.torque_from_lateral_accel_linear
 
   @staticmethod
-  def _get_params(ret: structs.CarParams, candidate, fingerprint, car_fw, experimental_long, docs):
+  def _get_params(ret: structs.CarParams, candidate, fingerprint, car_fw, experimental_long, docs) -> structs.CarParams:
     ret.carName = "gm"
     ret.safetyConfigs = [get_safety_config(structs.CarParams.SafetyModel.gm)]
     ret.autoResumeSng = False
diff --git a/selfdrive/car/honda/interface.py b/selfdrive/car/honda/interface.py
index 620e41313e..54df6c2579 100755
--- a/selfdrive/car/honda/interface.py
+++ b/selfdrive/car/honda/interface.py
@@ -25,7 +25,7 @@ class CarInterface(CarInterfaceBase):
       return CarControllerParams.NIDEC_ACCEL_MIN, interp(current_speed, ACCEL_MAX_BP, ACCEL_MAX_VALS)
 
   @staticmethod
-  def _get_params(ret: structs.CarParams, candidate, fingerprint, car_fw, experimental_long, docs):
+  def _get_params(ret: structs.CarParams, candidate, fingerprint, car_fw, experimental_long, docs) -> structs.CarParams:
     ret.carName = "honda"
 
     CAN = CanBus(ret, fingerprint)
diff --git a/selfdrive/car/hyundai/interface.py b/selfdrive/car/hyundai/interface.py
index 63e2271c64..4530704ed2 100644
--- a/selfdrive/car/hyundai/interface.py
+++ b/selfdrive/car/hyundai/interface.py
@@ -15,7 +15,7 @@ ENABLE_BUTTONS = (Buttons.RES_ACCEL, Buttons.SET_DECEL, Buttons.CANCEL)
 
 class CarInterface(CarInterfaceBase):
   @staticmethod
-  def _get_params(ret: structs.CarParams, candidate, fingerprint, car_fw, experimental_long, docs):
+  def _get_params(ret: structs.CarParams, candidate, fingerprint, car_fw, experimental_long, docs) -> structs.CarParams:
     ret.carName = "hyundai"
     ret.radarUnavailable = RADAR_START_ADDR not in fingerprint[1] or DBC[ret.carFingerprint]["radar"] is None
 
diff --git a/selfdrive/car/mazda/interface.py b/selfdrive/car/mazda/interface.py
index 9cb8797718..010490be6c 100755
--- a/selfdrive/car/mazda/interface.py
+++ b/selfdrive/car/mazda/interface.py
@@ -8,7 +8,7 @@ from openpilot.selfdrive.car.interfaces import CarInterfaceBase
 class CarInterface(CarInterfaceBase):
 
   @staticmethod
-  def _get_params(ret: structs.CarParams, candidate, fingerprint, car_fw, experimental_long, docs):
+  def _get_params(ret: structs.CarParams, candidate, fingerprint, car_fw, experimental_long, docs) -> structs.CarParams:
     ret.carName = "mazda"
     ret.safetyConfigs = [get_safety_config(structs.CarParams.SafetyModel.mazda)]
     ret.radarUnavailable = True
diff --git a/selfdrive/car/mock/interface.py b/selfdrive/car/mock/interface.py
index 9d01f6c691..d33cc7d164 100755
--- a/selfdrive/car/mock/interface.py
+++ b/selfdrive/car/mock/interface.py
@@ -7,7 +7,7 @@ from openpilot.selfdrive.car.interfaces import CarInterfaceBase
 class CarInterface(CarInterfaceBase):
 
   @staticmethod
-  def _get_params(ret: structs.CarParams, candidate, fingerprint, car_fw, experimental_long, docs):
+  def _get_params(ret: structs.CarParams, candidate, fingerprint, car_fw, experimental_long, docs) -> structs.CarParams:
     ret.carName = "mock"
     ret.mass = 1700.
     ret.wheelbase = 2.70
diff --git a/selfdrive/car/nissan/interface.py b/selfdrive/car/nissan/interface.py
index e9d8374d7d..4a9b31dacf 100644
--- a/selfdrive/car/nissan/interface.py
+++ b/selfdrive/car/nissan/interface.py
@@ -7,7 +7,7 @@ from openpilot.selfdrive.car.nissan.values import CAR
 class CarInterface(CarInterfaceBase):
 
   @staticmethod
-  def _get_params(ret: structs.CarParams, candidate, fingerprint, car_fw, experimental_long, docs):
+  def _get_params(ret: structs.CarParams, candidate, fingerprint, car_fw, experimental_long, docs) -> structs.CarParams:
     ret.carName = "nissan"
     ret.safetyConfigs = [get_safety_config(structs.CarParams.SafetyModel.nissan)]
     ret.autoResumeSng = False
diff --git a/selfdrive/car/subaru/interface.py b/selfdrive/car/subaru/interface.py
index e9ed1b2129..d392edc60b 100644
--- a/selfdrive/car/subaru/interface.py
+++ b/selfdrive/car/subaru/interface.py
@@ -8,7 +8,7 @@ from openpilot.selfdrive.car.subaru.values import CAR, GLOBAL_ES_ADDR, SubaruFla
 class CarInterface(CarInterfaceBase):
 
   @staticmethod
-  def _get_params(ret: structs.CarParams, candidate: CAR, fingerprint, car_fw, experimental_long, docs):
+  def _get_params(ret: structs.CarParams, candidate: CAR, fingerprint, car_fw, experimental_long, docs) -> structs.CarParams:
     ret.carName = "subaru"
     ret.radarUnavailable = True
     # for HYBRID CARS to be upstreamed, we need:
diff --git a/selfdrive/car/toyota/interface.py b/selfdrive/car/toyota/interface.py
index ee3f22f57c..39586a8de8 100644
--- a/selfdrive/car/toyota/interface.py
+++ b/selfdrive/car/toyota/interface.py
@@ -15,7 +15,7 @@ class CarInterface(CarInterfaceBase):
     return CarControllerParams.ACCEL_MIN, CarControllerParams.ACCEL_MAX
 
   @staticmethod
-  def _get_params(ret: structs.CarParams, candidate, fingerprint, car_fw, experimental_long, docs):
+  def _get_params(ret: structs.CarParams, candidate, fingerprint, car_fw, experimental_long, docs) -> structs.CarParams:
     ret.carName = "toyota"
     ret.safetyConfigs = [get_safety_config(structs.CarParams.SafetyModel.toyota)]
     ret.safetyConfigs[0].safetyParam = EPS_SCALE[candidate]
diff --git a/selfdrive/car/volkswagen/interface.py b/selfdrive/car/volkswagen/interface.py
index 0d4f1e0ee3..96f3493fe8 100644
--- a/selfdrive/car/volkswagen/interface.py
+++ b/selfdrive/car/volkswagen/interface.py
@@ -6,7 +6,7 @@ from openpilot.selfdrive.car.volkswagen.values import CAR, NetworkLocation, Tran
 
 class CarInterface(CarInterfaceBase):
   @staticmethod
-  def _get_params(ret: structs.CarParams, candidate: CAR, fingerprint, car_fw, experimental_long, docs):
+  def _get_params(ret: structs.CarParams, candidate: CAR, fingerprint, car_fw, experimental_long, docs) -> structs.CarParams:
     ret.carName = "volkswagen"
     ret.radarUnavailable = True