diff --git a/cereal/custom.capnp b/cereal/custom.capnp
index 33aef6df4f..3f92e43a3e 100644
--- a/cereal/custom.capnp
+++ b/cereal/custom.capnp
@@ -133,7 +133,8 @@ struct LongitudinalPlanSP @0xf35cc4560bbf6ec2 {
   }
 }
 
-struct CustomReserved3 @0xda96579883444c35 {
+struct CarParamsSP @0xda96579883444c35 {
+  flags @0 :UInt32;  # flags for car specific quirks in sunnypilot
 }
 
 struct CustomReserved4 @0x80ae746ee2596b11 {
diff --git a/cereal/log.capnp b/cereal/log.capnp
index f8000ec1eb..95f741ee3d 100644
--- a/cereal/log.capnp
+++ b/cereal/log.capnp
@@ -2569,7 +2569,7 @@ struct Event {
     modelManagerSP @108 :Custom.ModelManagerSP;
     longitudinalPlanSP @109 :Custom.LongitudinalPlanSP;
     onroadEventsSP @110 :List(Custom.OnroadEventSP);
-    customReserved4 @111 :Custom.CustomReserved4;
+    carParamsSP @111 :Custom.CarParamsSP;
     customReserved5 @112 :Custom.CustomReserved5;
     customReserved6 @113 :Custom.CustomReserved6;
     customReserved7 @114 :Custom.CustomReserved7;