diff --git a/nml/actions/action0properties.py b/nml/actions/action0properties.py
index c7015fa3..16ccf663 100644
--- a/nml/actions/action0properties.py
+++ b/nml/actions/action0properties.py
@@ -447,6 +447,7 @@ def zero_refit_mask(prop_num):
     ],
     "curve_speed_mod":                {"size": 2, "num": 0x2E, "unit_conversion": 256},
     "variant_group":                  {"size": 2, "num": 0x2F},
+    "extra_flags":                    {"size": 4, "num": 0x30},
 }
 # fmt: on
 
@@ -524,6 +525,7 @@ def prop15_test(value):
         zero_refit_mask(0x16),
     ],
     "variant_group":                {"size": 2, "num": 0x26},
+    "extra_flags":                  {"size": 4, "num": 0x27},
 }
 # fmt: on
 
@@ -592,6 +594,7 @@ def speed_fraction(value):
         zero_refit_mask(0x11),
     ],
     "variant_group":                {"size": 2, "num": 0x20},
+    "extra_flags":                  {"size": 4, "num": 0x21},
 }
 # fmt: on
 
@@ -652,6 +655,7 @@ def aircraft_is_large(value):
     ],
     "range":                        {"size": 2, "num": 0x1F},
     "variant_group":                {"size": 2, "num": 0x20},
+    "extra_flags":                  {"size": 4, "num": 0x21},
 }
 # fmt: on
 
diff --git a/nml/global_constants.py b/nml/global_constants.py
index cedfbb86..f5ccae7c 100644
--- a/nml/global_constants.py
+++ b/nml/global_constants.py
@@ -130,7 +130,7 @@ def constant_number(name, info, pos):
     "SHIP_FLAG_NO_BREAKDOWN_SMOKE": 6,
     "SHIP_FLAG_SPRITE_STACK": 7,
 
-    # aircrafts misc flags
+    # aircraft misc flags
     "AIRCRAFT_FLAG_2CC"  : 1,
     "AIRCRAFT_FLAG_AUTOREFIT": 4,
     "AIRCRAFT_FLAG_NO_BREAKDOWN_SMOKE": 6,
@@ -141,6 +141,12 @@ def constant_number(name, info, pos):
     "VEHICLE_FLAG_AUTOREFIT": 4,
     "VEHICLE_FLAG_NO_BREAKDOWN_SMOKE": 6,
 
+    # vehicle extra flags
+    "VEHICLE_FLAG_DISABLE_NEW_VEHICLE_MESSAGE"           : 0,
+    "VEHICLE_FLAG_DISABLE_EXCLUSIVE_PREVIEW"             : 1,
+    "VEHICLE_FLAG_SYNCHRONISE_VARIANT_EXCLUSIVE_PREVIEW" : 2,
+    "VEHICLE_FLAG_SYNCHRONISE_VARIANT_RELIABILITY"       : 3,
+
     # Graphic flags for waterfeatures
     "WATERFEATURE_ALTERNATIVE_SPRITES" : 0,