diff --git a/selfdrive/ui/onroad/alert_renderer.py b/selfdrive/ui/onroad/alert_renderer.py
index e8817f24b4..c529694df4 100644
--- a/selfdrive/ui/onroad/alert_renderer.py
+++ b/selfdrive/ui/onroad/alert_renderer.py
@@ -4,7 +4,7 @@ from dataclasses import dataclass
 from cereal import messaging, log
 from openpilot.selfdrive.ui.ui_state import ui_state
 from openpilot.system.hardware import TICI
-from openpilot.system.ui.lib.application import gui_app, FontWeight, DEFAULT_FPS
+from openpilot.system.ui.lib.application import gui_app, FontWeight
 from openpilot.system.ui.lib.text_measure import measure_text_cached
 from openpilot.system.ui.widgets import Widget
 from openpilot.system.ui.widgets.label import gui_text_box
@@ -76,7 +76,7 @@ class AlertRenderer(Widget):
     # Check if selfdriveState messages have stopped arriving
     if not sm.updated['selfdriveState']:
       recv_frame = sm.recv_frame['selfdriveState']
-      time_since_onroad = (sm.frame - ui_state.started_frame) / DEFAULT_FPS
+      time_since_onroad = time.monotonic() - ui_state.started_time
 
       # 1. Never received selfdriveState since going onroad
       waiting_for_startup = recv_frame < ui_state.started_frame
diff --git a/selfdrive/ui/onroad/model_renderer.py b/selfdrive/ui/onroad/model_renderer.py
index 932773755d..89bdb48ac9 100644
--- a/selfdrive/ui/onroad/model_renderer.py
+++ b/selfdrive/ui/onroad/model_renderer.py
@@ -3,6 +3,7 @@ import numpy as np
 import pyray as rl
 from cereal import messaging, car
 from dataclasses import dataclass, field
+from openpilot.common.filter_simple import FirstOrderFilter
 from openpilot.common.params import Params
 from openpilot.selfdrive.locationd.calibrationd import HEIGHT_INIT
 from openpilot.selfdrive.ui.ui_state import ui_state
@@ -49,7 +50,7 @@ class ModelRenderer(Widget):
     super().__init__()
     self._longitudinal_control = False
     self._experimental_mode = False
-    self._blend_factor = 1.0
+    self._blend_filter = FirstOrderFilter(1.0, 0.25, 1 / DEFAULT_FPS)
     self._prev_allow_throttle = True
     self._lane_line_probs = np.zeros(4, dtype=np.float32)
     self._road_edge_stds = np.zeros(2, dtype=np.float32)
@@ -277,6 +278,9 @@ class ModelRenderer(Widget):
     if not self._path.projected_points.size:
       return
 
+    allow_throttle = sm['longitudinalPlan'].allowThrottle or not self._longitudinal_control
+    self._blend_filter.update(int(allow_throttle))
+
     if self._experimental_mode:
       # Draw with acceleration coloring
       if len(self._exp_gradient['colors']) > 1:
@@ -284,23 +288,9 @@ class ModelRenderer(Widget):
       else:
         draw_polygon(self._rect, self._path.projected_points, rl.Color(255, 255, 255, 30))
     else:
-      # Draw with throttle/no throttle gradient
-      allow_throttle = sm['longitudinalPlan'].allowThrottle or not self._longitudinal_control
-
-      # Start transition if throttle state changes
-      if allow_throttle != self._prev_allow_throttle:
-        self._prev_allow_throttle = allow_throttle
-        self._blend_factor = max(1.0 - self._blend_factor, 0.0)
-
-      # Update blend factor
-      if self._blend_factor < 1.0:
-        self._blend_factor = min(self._blend_factor + PATH_BLEND_INCREMENT, 1.0)
-
-      begin_colors = NO_THROTTLE_COLORS if allow_throttle else THROTTLE_COLORS
-      end_colors = THROTTLE_COLORS if allow_throttle else NO_THROTTLE_COLORS
-
-      # Blend colors based on transition
-      blended_colors = self._blend_colors(begin_colors, end_colors, self._blend_factor)
+      # Blend throttle/no throttle colors based on transition
+      blend_factor = round(self._blend_filter.x * 100) / 100
+      blended_colors = self._blend_colors(NO_THROTTLE_COLORS, THROTTLE_COLORS, blend_factor)
       gradient = {
         'start': (0.0, 1.0),  # Bottom of path
         'end': (0.0, 0.0),  # Top of path
diff --git a/selfdrive/ui/ui_state.py b/selfdrive/ui/ui_state.py
index c4a2c0ca11..13532620cb 100644
--- a/selfdrive/ui/ui_state.py
+++ b/selfdrive/ui/ui_state.py
@@ -59,6 +59,7 @@ class UIState:
     # UI Status tracking
     self.status: UIStatus = UIStatus.DISENGAGED
     self.started_frame: int = 0
+    self.started_time: float = 0.0
     self._engaged_prev: bool = False
     self._started_prev: bool = False
 
@@ -131,6 +132,7 @@ class UIState:
       if self.started:
         self.status = UIStatus.DISENGAGED
         self.started_frame = self.sm.frame
+        self.started_time = time.monotonic()
 
       self._started_prev = self.started