diff --git a/car.capnp b/car.capnp
index a5dba27e9850d4..83c71a3874946d 100644
--- a/car.capnp
+++ b/car.capnp
@@ -361,6 +361,7 @@ struct CarParams {
   dashcamOnly @41: Bool;
   transmissionType @43 :TransmissionType;
   carFw @44 :List(CarFw);
+  radarTimeStep @45: Float32;  # time delta between radar updates
 
   struct LateralPIDTuning {
     kpBP @0 :List(Float32);
@@ -379,7 +380,6 @@ struct CarParams {
     deadzoneV @5 :List(Float32);
   }
 
-
   struct LateralINDITuning {
     outerLoopGain @0 :Float32;
     innerLoopGain @1 :Float32;