diff --git a/selfdrive/test/test_onroad.py b/selfdrive/test/test_onroad.py
index a1ac95d419..ef93d6003e 100755
--- a/selfdrive/test/test_onroad.py
+++ b/selfdrive/test/test_onroad.py
@@ -1,8 +1,10 @@
 #!/usr/bin/env python3
+import json
 import os
-import time
 import subprocess
+import time
 import unittest
+from collections import Counter
 from pathlib import Path
 
 import cereal.messaging as messaging
@@ -128,6 +130,16 @@ class TestOnroad(unittest.TestCase):
 
     cls.lr = list(LogReader(os.path.join(str(cls.segments[1]), "rlog.bz2")))
 
+  def test_cloudlog_size(self):
+    msgs = [m for m in self.lr if m.which() == 'logMessage']
+
+    total_size = sum(len(m.as_builder().to_bytes()) for m in msgs)
+    self.assertLess(total_size, 2.5e5)
+
+    cnt = Counter([json.loads(m.logMessage)['filename'] for m in msgs])
+    big_logs = [f for f, n in cnt.most_common(3) if n / sum(cnt.values()) > 30.]
+    self.assertEqual(len(big_logs), 0, f"Log spam: {big_logs}")
+
   def test_cpu_usage(self):
     proclogs = [m for m in self.lr if m.which() == 'procLog']
     self.assertGreater(len(proclogs), service_list['procLog'].frequency * 45, "insufficient samples")