ACC: Don't autoresume if there is a slow car in front

selfdrive/car/tesla/ACC_module.py

@@ -284,14 +284,16 @@ def _should_autoengage_cc(self, CS, lead_car=None):
                     and CS.pcm_acc_status == 1
                     and CS.v_ego >= self.MIN_CRUISE_SPEED_MS
                     and _current_time_millis() > self.fast_decel_time + 2000)
+
+    no_slow_lead = not lead_car or lead_car.vRel >= 0
 
     # "Autoresume" mode allows cruise to engage even after brake events, but
     # shouldn't trigger DURING braking.
     autoresume_ready = self.autoresume and CS.a_ego >= 0.1
 
     braked = self.user_has_braked or self.has_gone_below_min_speed
 
-    return cruise_ready and (autoresume_ready or not braked)
+    return cruise_ready and no_slow_lead and (autoresume_ready or not braked)
 
   def _fast_decel_required(self, CS, lead_car):
     """ Identifies situations which call for rapid deceleration. """