(svn r17688) -Fix (r17684): incorrect comments

src/roadveh.h

@@ -89,7 +89,7 @@ void RoadVehUpdateCache(RoadVehicle *v);
 /** Cached oftenly queried (NewGRF) values */
 struct RoadVehicleCache {
 	byte cached_veh_length;
-	EngineID first_engine;   ///< cached EngineID of the front vehicle. INVALID_VEHICLE for the front vehicle itself.
+	EngineID first_engine;   ///< cached EngineID of the front vehicle. INVALID_ENGINE for the front vehicle itself.
 };
 
 /**

src/train.h

@@ -96,7 +96,7 @@ struct TrainCache {
 	byte cached_vis_effect;
 	byte user_def_data;
 
-	EngineID first_engine;  ///< cached EngineID of the front vehicle. INVALID_VEHICLE for the front vehicle itself.
+	EngineID first_engine;  ///< cached EngineID of the front vehicle. INVALID_ENGINE for the front vehicle itself.
 };
 
 /**