diff --git a/selfdrive/controls/lib/longitudinal_mpc_lib/long_mpc.py b/selfdrive/controls/lib/longitudinal_mpc_lib/long_mpc.py
index df6d8e0fb64316..672282e40bb76f 100644
--- a/selfdrive/controls/lib/longitudinal_mpc_lib/long_mpc.py
+++ b/selfdrive/controls/lib/longitudinal_mpc_lib/long_mpc.py
@@ -51,14 +51,14 @@
 MAX_BRAKE = 9.81
 
 
-def get_stopped_equivalence_factor(v_lead):
-  return T_REACT * v_lead + (v_lead*v_lead) / (2 * MAX_BRAKE)
+def get_stopped_equivalence_factor(v_lead, t_react=T_REACT):
+  return t_react * v_lead + (v_lead*v_lead) / (2 * MAX_BRAKE)
 
-def get_safe_obstacle_distance(v_ego):
-  return 2 * T_REACT * v_ego + (v_ego*v_ego) / (2 * MAX_BRAKE) + 4.0
+def get_safe_obstacle_distance(v_ego, t_react=T_REACT):
+  return 2 * t_react * v_ego + (v_ego*v_ego) / (2 * MAX_BRAKE) + 4.0
 
-def desired_follow_distance(v_ego, v_lead):
-  return get_safe_obstacle_distance(v_ego) - get_stopped_equivalence_factor(v_lead)
+def desired_follow_distance(v_ego, v_lead, t_react=T_REACT):
+  return get_safe_obstacle_distance(v_ego, t_react) - get_stopped_equivalence_factor(v_lead, t_react)
 
 
 def gen_long_model():
@@ -83,9 +83,10 @@ def gen_long_model():
 
   # live parameters
   x_obstacle = SX.sym('x_obstacle')
+  desired_TR = SX.sym('desired_TR')
   a_min = SX.sym('a_min')
   a_max = SX.sym('a_max')
-  model.p = vertcat(a_min, a_max, x_obstacle)
+  model.p = vertcat(a_min, a_max, x_obstacle, desired_TR)
 
   # dynamics model
   f_expl = vertcat(v_ego, a_ego, j_ego)
@@ -118,11 +119,12 @@ def gen_long_mpc_solver():
 
   a_min, a_max = ocp.model.p[0], ocp.model.p[1]
   x_obstacle = ocp.model.p[2]
+  desired_TR = ocp.model.p[3]
 
   ocp.cost.yref = np.zeros((COST_DIM, ))
   ocp.cost.yref_e = np.zeros((COST_E_DIM, ))
 
-  desired_dist_comfort = get_safe_obstacle_distance(v_ego)
+  desired_dist_comfort = get_safe_obstacle_distance(v_ego, desired_TR)
 
   # The main cost in normal operation is how close you are to the "desired" distance
   # from an obstacle at every timestep. This obstacle can be a lead car
@@ -148,7 +150,7 @@ def gen_long_mpc_solver():
 
   x0 = np.zeros(X_DIM)
   ocp.constraints.x0 = x0
-  ocp.parameter_values = np.array([-1.2, 1.2, 0.0])
+  ocp.parameter_values = np.array([-1.2, 1.2, 0.0, T_REACT])  # defaults
 
   # We put all constraint cost weights to 0 and only set them at runtime
   cost_weights = np.zeros(CONSTR_DIM)
@@ -186,8 +188,10 @@ def gen_long_mpc_solver():
 
 
 class LongitudinalMpc():
-  def __init__(self, e2e=False):
+  def __init__(self, e2e=False, desired_TR=T_REACT):
     self.e2e = e2e
+    self.desired_TR = desired_TR
+    self.v_ego = 0.
     self.reset()
     self.accel_limit_arr = np.zeros((N+1, 2))
     self.accel_limit_arr[:,0] = -1.2
@@ -205,7 +209,7 @@ def reset(self):
     self.solver.cost_set(N, "yref", self.yref[N][:COST_E_DIM])
     self.x_sol = np.zeros((N+1, X_DIM))
     self.u_sol = np.zeros((N,1))
-    self.params = np.zeros((N+1,3))
+    self.params = np.zeros((N+1,4))
     for i in range(N+1):
       self.solver.set(i, 'x', np.zeros(X_DIM))
     self.last_cloudlog_t = 0
@@ -222,7 +226,17 @@ def set_weights(self):
       self.set_weights_for_lead_policy()
 
   def set_weights_for_lead_policy(self):
-    W = np.asfortranarray(np.diag([X_EGO_OBSTACLE_COST, X_EGO_COST, V_EGO_COST, A_EGO_COST, J_EGO_COST]))
+    # WARNING: deceleration tests with these costs:
+    # 1.0 TR fails at 3 m/s/s test
+    # 1.1 TR fails at 3+ m/s/s test
+    # 1.2-1.8 TR succeeds at all tests with no FCW
+
+    TRs = [1.2, 1.8, 2.7]
+    x_ego_obstacle_cost_multiplier = interp(self.desired_TR, TRs, [3., 1.0, 0.1])
+    j_ego_cost_multiplier = interp(self.desired_TR, TRs, [0.5, 1.0, 1.0])
+    d_zone_cost_multiplier = interp(self.desired_TR, TRs, [4., 1.0, 1.0])
+
+    W = np.asfortranarray(np.diag([X_EGO_OBSTACLE_COST * x_ego_obstacle_cost_multiplier, X_EGO_COST, V_EGO_COST, A_EGO_COST, J_EGO_COST * j_ego_cost_multiplier]))
     for i in range(N):
       self.solver.cost_set(i, 'W', W)
     # Setting the slice without the copy make the array not contiguous,
@@ -230,7 +244,7 @@ def set_weights_for_lead_policy(self):
     self.solver.cost_set(N, 'W', np.copy(W[:COST_E_DIM, :COST_E_DIM]))
 
     # Set L2 slack cost on lower bound constraints
-    Zl = np.array([LIMIT_COST, LIMIT_COST, LIMIT_COST, DANGER_ZONE_COST])
+    Zl = np.array([LIMIT_COST, LIMIT_COST, LIMIT_COST, DANGER_ZONE_COST * d_zone_cost_multiplier])
     for i in range(N):
       self.solver.cost_set(i, 'Zl', Zl)
 
@@ -291,7 +305,12 @@ def set_accel_limits(self, min_a, max_a):
     self.cruise_min_a = min_a
     self.cruise_max_a = max_a
 
+  def set_desired_TR(self, desired_TR):
+    self.desired_TR = clip(desired_TR, 1.2, 2.7)
+    self.set_weights()
+
   def update(self, carstate, radarstate, v_cruise):
+    self.v_ego = carstate.vEgo
     v_ego = self.x0[1]
     self.status = radarstate.leadOne.status or radarstate.leadTwo.status
 
@@ -305,8 +324,8 @@ def update(self, carstate, radarstate, v_cruise):
     # To estimate a safe distance from a moving lead, we calculate how much stopping
     # distance that lead needs as a minimum. We can add that to the current distance
     # and then treat that as a stopped car/obstacle at this new distance.
-    lead_0_obstacle = lead_xv_0[:,0] + get_stopped_equivalence_factor(lead_xv_0[:,1])
-    lead_1_obstacle = lead_xv_1[:,0] + get_stopped_equivalence_factor(lead_xv_1[:,1])
+    lead_0_obstacle = lead_xv_0[:,0] + get_stopped_equivalence_factor(lead_xv_0[:,1], self.desired_TR)
+    lead_1_obstacle = lead_xv_1[:,0] + get_stopped_equivalence_factor(lead_xv_1[:,1], self.desired_TR)
 
     # Fake an obstacle for cruise, this ensures smooth acceleration to set speed
     # when the leads are no factor.
@@ -315,11 +334,12 @@ def update(self, carstate, radarstate, v_cruise):
     v_cruise_clipped = np.clip(v_cruise * np.ones(N+1),
                                cruise_lower_bound,
                                cruise_upper_bound)
-    cruise_obstacle = T_IDXS*v_cruise_clipped + get_safe_obstacle_distance(v_cruise_clipped)
+    cruise_obstacle = T_IDXS*v_cruise_clipped + get_safe_obstacle_distance(v_cruise_clipped, self.desired_TR)
 
     x_obstacles = np.column_stack([lead_0_obstacle, lead_1_obstacle, cruise_obstacle])
     self.source = SOURCES[np.argmin(x_obstacles[0])]
     self.params[:,2] = np.min(x_obstacles, axis=1)
+    self.params[:,3] = self.desired_TR
 
     self.run()
     if (np.any(lead_xv_0[:,0] - self.x_sol[:,0] < CRASH_DISTANCE) and
@@ -338,8 +358,9 @@ def update_with_xva(self, x, v, a):
     self.accel_limit_arr[:,0] = -10.
     self.accel_limit_arr[:,1] = 10.
     x_obstacle = 1e5*np.ones((N+1))
+    desired_TR = T_REACT*np.ones((N+1))
     self.params = np.concatenate([self.accel_limit_arr,
-                             x_obstacle[:,None]], axis=1)
+                             x_obstacle[:,None], desired_TR[:,None]], axis=1)
     self.run()
 
 
diff --git a/selfdrive/controls/lib/longitudinal_planner.py b/selfdrive/controls/lib/longitudinal_planner.py
index 051a68a7415df9..3c0e3f95291a71 100755
--- a/selfdrive/controls/lib/longitudinal_planner.py
+++ b/selfdrive/controls/lib/longitudinal_planner.py
@@ -88,6 +88,7 @@ def update(self, sm, CP):
     accel_limits_turns[1] = max(accel_limits_turns[1], self.a_desired - 0.05)
     self.mpc.set_accel_limits(accel_limits_turns[0], accel_limits_turns[1])
     self.mpc.set_cur_state(self.v_desired, self.a_desired)
+    # self.mpc.set_desired_TR(1.8)
     self.mpc.update(sm['carState'], sm['radarState'], v_cruise)
     self.v_desired_trajectory = np.interp(T_IDXS[:CONTROL_N], T_IDXS_MPC, self.mpc.v_solution)
     self.a_desired_trajectory = np.interp(T_IDXS[:CONTROL_N], T_IDXS_MPC, self.mpc.a_solution)