diff --git a/selfdrive/car/car_helpers.py b/selfdrive/car/car_helpers.py
index 45db20065f..45ad32f666 100644
--- a/selfdrive/car/car_helpers.py
+++ b/selfdrive/car/car_helpers.py
@@ -89,7 +89,7 @@ def fingerprint(can_recv: CanRecvCallable, can_send: CanSendCallable, set_obd_mu
 
   start_time = time.monotonic()
   if not skip_fw_query:
-    if cached_params is not None and len(cached_params.carFw) > 0 and \
+    if cached_params is not None and cached_params.carName != "mock" and len(cached_params.carFw) > 0 and \
        cached_params.carVin is not VIN_UNKNOWN and not disable_fw_cache:
       carlog.warning("Using cached CarParams")
       vin_rx_addr, vin_rx_bus, vin = -1, -1, cached_params.carVin
diff --git a/selfdrive/car/card.py b/selfdrive/car/card.py
index cd8740dd5c..7e5342abf2 100755
--- a/selfdrive/car/card.py
+++ b/selfdrive/car/card.py
@@ -60,6 +60,7 @@ def can_comm_callbacks(logcan: messaging.SubSocket, sendcan: messaging.PubSocket
 
 
 def convert_to_capnp(CP: CarParams) -> car.CarParams:
+  # TODO: better name or support CarState, CarControl, etc.
   CP_dict = dataclasses.asdict(CP)
   del CP_dict['lateralTuning']
   CP_capnp = car.CarParams.new_message(**CP_dict)
diff --git a/selfdrive/test/process_replay/process_replay.py b/selfdrive/test/process_replay/process_replay.py
index 055293f16f..661a85cdd5 100755
--- a/selfdrive/test/process_replay/process_replay.py
+++ b/selfdrive/test/process_replay/process_replay.py
@@ -22,8 +22,9 @@ from openpilot.common.prefix import OpenpilotPrefix
 from openpilot.common.timeout import Timeout
 from openpilot.common.realtime import DT_CTRL
 from panda.python import ALTERNATIVE_EXPERIENCE
-from openpilot.selfdrive.car.card import can_comm_callbacks
+from openpilot.selfdrive.car.card import can_comm_callbacks, convert_to_capnp
 from openpilot.selfdrive.car.car_helpers import get_car, interfaces
+from openpilot.selfdrive.car.data_structures import CarParams
 from openpilot.system.manager.process_config import managed_processes
 from openpilot.selfdrive.test.process_replay.vision_meta import meta_from_camera_state, available_streams
 from openpilot.selfdrive.test.process_replay.migration import migrate_all
@@ -349,8 +350,8 @@ def get_car_params_callback(rc, pm, msgs, fingerprint):
     sendcan = DummySocket()
 
     canmsgs = [msg for msg in msgs if msg.which() == "can"]
-    cached_params = params.get("CarParamsCache")
-    has_cached_cp = cached_params is not None
+    cached_params_raw = params.get("CarParamsCache")
+    has_cached_cp = cached_params_raw is not None
     assert len(canmsgs) != 0, "CAN messages are required for fingerprinting"
     assert os.environ.get("SKIP_FW_QUERY", False) or has_cached_cp, \
             "CarParamsCache is required for fingerprinting. Make sure to keep carParams msgs in the logs."
@@ -358,13 +359,19 @@ def get_car_params_callback(rc, pm, msgs, fingerprint):
     for m in canmsgs[:300]:
       can.send(m.as_builder().to_bytes())
     can_callbacks = can_comm_callbacks(can, sendcan)
+    # TODO: clean this up a bit
+    cached_params = None
+    if has_cached_cp:
+      with car.CarParams.from_bytes(cached_params_raw) as _cached_params:
+        # TODO: even more generic?
+        cached_params = CarParams(carName=_cached_params.carName, carFw=_cached_params.carFw, carVin=_cached_params.carVin)
     CP = get_car(*can_callbacks, lambda obd: None, Params().get_bool("ExperimentalLongitudinalEnabled"), cached_params=cached_params).CP
 
     if not params.get_bool("DisengageOnAccelerator"):
       CP.alternativeExperience |= ALTERNATIVE_EXPERIENCE.DISABLE_DISENGAGE_ON_GAS
 
-  params.put("CarParams", CP.to_bytes())
-  return CP
+  params.put("CarParams", convert_to_capnp(CP).to_bytes())
+  # return CP  # TODO: this isn't used?
 
 
 def controlsd_rcv_callback(msg, cfg, frame):