diff --git a/selfdrive/car/chrysler/interface.py b/selfdrive/car/chrysler/interface.py
index ec041f2f3a..ab5bf50f46 100755
--- a/selfdrive/car/chrysler/interface.py
+++ b/selfdrive/car/chrysler/interface.py
@@ -93,6 +93,7 @@ class CarInterface(CarInterfaceBase):
 
   def _update(self, c):
     ret = self.CS.update(self.cp, self.cp_cam)
+    self.sp_update_params()
 
     buttonEvents = []
 
diff --git a/selfdrive/car/gm/interface.py b/selfdrive/car/gm/interface.py
index 869ab3b0a7..1f82c63587 100755
--- a/selfdrive/car/gm/interface.py
+++ b/selfdrive/car/gm/interface.py
@@ -251,6 +251,7 @@ class CarInterface(CarInterfaceBase):
   # returns a car.CarState
   def _update(self, c):
     ret = self.CS.update(self.cp, self.cp_cam, self.cp_loopback)
+    self.sp_update_params()
 
     buttonEvents = []
 
diff --git a/selfdrive/car/honda/interface.py b/selfdrive/car/honda/interface.py
index bc8e7be4a4..629514628a 100755
--- a/selfdrive/car/honda/interface.py
+++ b/selfdrive/car/honda/interface.py
@@ -311,6 +311,7 @@ class CarInterface(CarInterfaceBase):
   # returns a car.CarState
   def _update(self, c):
     ret = self.CS.update(self.cp, self.cp_cam, self.cp_body)
+    self.sp_update_params()
 
     buttonEvents = []
 
diff --git a/selfdrive/car/hyundai/interface.py b/selfdrive/car/hyundai/interface.py
index bc7600dd77..646f9dc12d 100644
--- a/selfdrive/car/hyundai/interface.py
+++ b/selfdrive/car/hyundai/interface.py
@@ -323,6 +323,7 @@ class CarInterface(CarInterfaceBase):
 
   def _update(self, c):
     ret = self.CS.update(self.cp, self.cp_cam)
+    self.sp_update_params()
 
     buttonEvents = []
 
diff --git a/selfdrive/car/interfaces.py b/selfdrive/car/interfaces.py
index b9bc662ebb..e6c37c9124 100644
--- a/selfdrive/car/interfaces.py
+++ b/selfdrive/car/interfaces.py
@@ -98,6 +98,8 @@ class CarInterfaceBase(ABC):
     self.mads_event_lock = True
     self.gap_button_counter = 0
     self.experimental_mode_hold = False
+    self.experimental_mode = self.param_s.get_bool("ExperimentalMode")
+    self._frame = 0
 
   @staticmethod
   def get_pid_accel_limits(CP, current_speed, cruise_speed):
@@ -419,14 +421,14 @@ class CarInterfaceBase(ABC):
   def toggle_exp_mode(self, gap_pressed):
     if not self.CP.openpilotLongitudinalControl:
       return None
-    experimental_mode = self.param_s.get_bool("ExperimentalMode")
     if gap_pressed:
       if not self.experimental_mode_hold:
         self.gap_button_counter += 1
         if self.gap_button_counter > 50:
           self.gap_button_counter = 0
           self.experimental_mode_hold = True
-          self.param_s.put_bool("ExperimentalMode", not experimental_mode)
+          self.experimental_mode = self.param_s.get_bool("ExperimentalMode")
+          self.param_s.put_bool("ExperimentalMode", not self.experimental_mode)
     else:
       self.gap_button_counter = 0
       self.experimental_mode_hold = False
@@ -494,6 +496,12 @@ class CarInterfaceBase(ABC):
 
     return events, cs_out
 
+  def sp_update_params(self):
+    self._frame += 1
+    if self._frame % 300 == 0:
+      self._frame = 0
+      self.experimental_mode = self.param_s.get_bool("ExperimentalMode")
+
 class RadarInterfaceBase(ABC):
   def __init__(self, CP):
     self.rcp = None
diff --git a/selfdrive/car/mazda/interface.py b/selfdrive/car/mazda/interface.py
index 07fe8b7ebc..3d1e24ebac 100755
--- a/selfdrive/car/mazda/interface.py
+++ b/selfdrive/car/mazda/interface.py
@@ -57,6 +57,7 @@ class CarInterface(CarInterfaceBase):
   # returns a car.CarState
   def _update(self, c):
     ret = self.CS.update(self.cp, self.cp_cam)
+    self.sp_update_params()
 
     buttonEvents = []
 
diff --git a/selfdrive/car/nissan/interface.py b/selfdrive/car/nissan/interface.py
index 580b34c842..dbead09803 100644
--- a/selfdrive/car/nissan/interface.py
+++ b/selfdrive/car/nissan/interface.py
@@ -44,6 +44,7 @@ class CarInterface(CarInterfaceBase):
   # returns a car.CarState
   def _update(self, c):
     ret = self.CS.update(self.cp, self.cp_adas, self.cp_cam)
+    self.sp_update_params()
 
     buttonEvents = []
     #be = car.CarState.ButtonEvent.new_message()
diff --git a/selfdrive/car/subaru/interface.py b/selfdrive/car/subaru/interface.py
index 7dfd9c367e..f756bf3b4d 100644
--- a/selfdrive/car/subaru/interface.py
+++ b/selfdrive/car/subaru/interface.py
@@ -111,6 +111,7 @@ class CarInterface(CarInterfaceBase):
   def _update(self, c):
 
     ret = self.CS.update(self.cp, self.cp_cam, self.cp_body)
+    self.sp_update_params()
 
     buttonEvents = []
 
diff --git a/selfdrive/car/toyota/interface.py b/selfdrive/car/toyota/interface.py
index 9b888d9326..c42e352117 100644
--- a/selfdrive/car/toyota/interface.py
+++ b/selfdrive/car/toyota/interface.py
@@ -244,6 +244,7 @@ class CarInterface(CarInterfaceBase):
   # returns a car.CarState
   def _update(self, c):
     ret = self.CS.update(self.cp, self.cp_cam)
+    self.sp_update_params()
 
     buttonEvents = []
 
diff --git a/selfdrive/car/volkswagen/interface.py b/selfdrive/car/volkswagen/interface.py
index e6347bc5b0..f8a83aafb3 100644
--- a/selfdrive/car/volkswagen/interface.py
+++ b/selfdrive/car/volkswagen/interface.py
@@ -223,6 +223,7 @@ class CarInterface(CarInterfaceBase):
   # returns a car.CarState
   def _update(self, c):
     ret = self.CS.update(self.cp, self.cp_cam, self.cp_ext, self.CP.transmissionType)
+    self.sp_update_params()
 
     buttonEvents = []