--- a/src/command.cpp	Wed Apr 04 12:43:43 2007 +0000
+++ b/src/command.cpp	Wed Apr 04 14:21:46 2007 +0000
@@ -455,13 +455,17 @@
 	 * restrictions which may cause the test run to fail (the previous
 	 * road fragments still stay there and the town won't let you
 	 * disconnect the road system), but the exec will succeed and this
-	 * fact will trigger an assertion failure. --pasky */
+	 * fact will trigger an assertion failure. --pasky
+	 * CMD_CLONE_VEHICLE: You can only refit vehicles once they have been
+	 * bought, so you can't estimate the cost of cloning if the vehicle to be
+	 * cloned has been refitted. */
 	notest =
 		(cmd & 0xFF) == CMD_CLEAR_AREA ||
 		(cmd & 0xFF) == CMD_CONVERT_RAIL ||
 		(cmd & 0xFF) == CMD_LEVEL_LAND ||
 		(cmd & 0xFF) == CMD_REMOVE_ROAD ||
-		(cmd & 0xFF) == CMD_REMOVE_LONG_ROAD;
+		(cmd & 0xFF) == CMD_REMOVE_LONG_ROAD ||
+		(cmd & 0xFF) == CMD_CLONE_VEHICLE;
 
 	_docommand_recursive = 1;
 

--- a/src/vehicle.cpp	Wed Apr 04 12:43:43 2007 +0000
+++ b/src/vehicle.cpp	Wed Apr 04 14:21:46 2007 +0000
@@ -1807,10 +1807,9 @@
 	w_front = NULL;
 	w_rear = NULL;
 
-
 	/*
 	 * v_front is the front engine in the original vehicle
-	 * v is the car/vehicle of the original vehicle, that is currently being copied
+	 * v is the car/vehicle of the original vehicle that is currently being copied
 	 * w_front is the front engine of the cloned vehicle
 	 * w is the car/vehicle currently being cloned
 	 * w_rear is the rear end of the cloned train. It's used to add more cars and is only used by trains
@@ -1855,11 +1854,18 @@
 			Vehicle *v2 = v;
 			do {
 				if (v2->cargo_type != w2->cargo_type || v2->cargo_subtype != w2->cargo_subtype) {
-					/* We can't pay for refitting because we can't estimate refitting costs for a vehicle before it's build.
-					 * If we pay for it anyway, the cost and the estimated cost will not be the same and we will have an assert.
-					 * We need to check the whole chain if it is a train because some newgrf articulated engines can refit some units only (and not the front) */
-					DoCommand(0, w->index, v2->cargo_type | (v2->cargo_subtype << 8), flags, GetCmdRefitVeh(v));
-					break; // We learned that the engine in question needed a refit. No need to check anymore
+					/* We need to check the whole chain if it is a train
+					 * because some newgrf articulated engines can refit some
+					 * units only (and not the front). */
+					cost = DoCommand(0, w->index, v2->cargo_type | (v2->cargo_subtype << 8), flags, GetCmdRefitVeh(v));
+					if (CmdFailed(cost)) return cost;
+
+					total_cost += cost;
+
+					/* The refit command will refit all the remaining
+					 * articulated parts if possible, so we don't need to
+					 * carry on checking. */
+					break;
 				}
 			} while (v->type == VEH_TRAIN && (w2 = w2->next) != NULL && (v2 = v2->next) != NULL);