diff -r e17a18bb827f src/lang/english.txt
--- a/src/lang/english.txt	Sat Oct 25 22:00:51 2008 +0000
+++ b/src/lang/english.txt	Sun Oct 26 16:32:18 2008 +0100
@@ -2939,7 +2939,7 @@ STR_TIMETABLE_TOTAL_TIME                
 STR_TIMETABLE_TOTAL_TIME                                        :This timetable will take {STRING1} to complete
 STR_TIMETABLE_TOTAL_TIME_INCOMPLETE                             :This timetable will take at least {STRING1} to complete (not all timetabled)
 STR_TIMETABLE_AUTOFILL                                          :{BLACK}Autofill
-STR_TIMETABLE_AUTOFILL_TOOLTIP                                  :{BLACK}Fill the timetable automatically with the values from the first journey
+STR_TIMETABLE_AUTOFILL_TOOLTIP                                  :{BLACK}Fill the timetable automatically with the values from the first journey (CTRL-click to avoid clearing the timetable)
 
 ##id 0x9000
 STR_9000_ROAD_VEHICLE_IN_THE_WAY                                :{WHITE}Road vehicle in the way
diff -r e17a18bb827f src/timetable_cmd.cpp
--- a/src/timetable_cmd.cpp	Sat Oct 25 22:00:51 2008 +0000
+++ b/src/timetable_cmd.cpp	Sun Oct 26 16:32:18 2008 +0100
@@ -133,7 +133,9 @@ CommandCost CmdSetVehicleOnTime(TileInde
  * @param tile Not used.
  * @param flags Operation to perform.
  * @param p1 Vehicle index.
- * @param p2 Set to 1 to enable, 0 to disable.
+ * @param p2 Various bitstuffed elements
+ * - p2 = (bit 0) - Set to 1 to enable, 0 to disable autofill.
+ * - p2 = (bit 1) - Set to 1 for non-destructive mode (do not clear timetable)
  */
 CommandCost CmdAutofillTimetable(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
 {
@@ -146,19 +148,23 @@ CommandCost CmdAutofillTimetable(TileInd
 	if (!CheckOwnership(v->owner)) return CMD_ERROR;
 
 	if (flags & DC_EXEC) {
-		if (p2 == 1) {
+		if (HasBit(p2, 0)) {
 			/* Start autofilling the timetable, which clears all the current
 			 * timings and clears the "timetable has started" bit. */
 			SetBit(v->vehicle_flags, VF_AUTOFILL_TIMETABLE);
 			ClrBit(v->vehicle_flags, VF_TIMETABLE_STARTED);
 
-			for (Order *order = GetVehicleOrder(v, 0); order != NULL; order = order->next) {
-				order->wait_time = 0;
-				order->travel_time = 0;
+			if (!HasBit(p2, 1)) {
+				for (Order *order = GetVehicleOrder(v, 0); order != NULL; order = order->next) {
+					order->wait_time = 0;
+					order->travel_time = 0;
+				}
+
+				v->current_order.wait_time = 0;
+				v->current_order.travel_time = 0;
 			}
 
-			v->current_order.wait_time = 0;
-			v->current_order.travel_time = 0;
+			v->lateness_counter = 0;
 		} else {
 			ClrBit(v->vehicle_flags, VF_AUTOFILL_TIMETABLE);
 		}
@@ -179,33 +185,45 @@ void UpdateVehicleTimetable(Vehicle *v, 
 	v->current_order_time = 0;
 
 	if (!_settings_game.order.timetabling) return;
+
+	bool just_started = false;
 
 	/* Make sure the timetable only starts when the vehicle reaches the first
 	 * order, not when travelling from the depot to the first station. */
 	if (v->cur_order_index == 0 && !HasBit(v->vehicle_flags, VF_TIMETABLE_STARTED)) {
 		SetBit(v->vehicle_flags, VF_TIMETABLE_STARTED);
-		return;
+		just_started = true;
 	}
 
 	if (!HasBit(v->vehicle_flags, VF_TIMETABLE_STARTED)) return;
 
 	if (HasBit(v->vehicle_flags, VF_AUTOFILL_TIMETABLE)) {
-		if (timetabled == 0) {
+		if (travelling) {
+			/* Need to clear that now as otherwise we are not able to reduce the wait time */
+			v->current_order.wait_time = 0;
+		}
+
+		if (just_started) return;
+
+		if (!v->current_order.IsType(OT_CONDITIONAL)) {
 			/* Round the time taken up to the nearest day, as this will avoid
 			 * confusion for people who are timetabling in days, and can be
 			 * adjusted later by people who aren't. */
 			time_taken = (((time_taken - 1) / DAY_TICKS) + 1) * DAY_TICKS;
 
-			if (!v->current_order.IsType(OT_CONDITIONAL)) {
-				ChangeTimetable(v, v->cur_order_index, time_taken, travelling);
-			}
-			return;
-		} else if (v->cur_order_index == 0) {
-			/* Otherwise if we're at the beginning and it already has a value,
-			 * assume that autofill is finished and turn it off again. */
+			ChangeTimetable(v, v->cur_order_index, time_taken, travelling);
+		}
+
+		if (v->cur_order_index == 0 && travelling) {
+			/* If we just started we would have returned earlier and have not reached
+			 * this code. So obviously, we have completed our round: So turn autofill
+			 * off again. */
 			ClrBit(v->vehicle_flags, VF_AUTOFILL_TIMETABLE);
 		}
-	}
+		return;
+	}
+
+	if (just_started) return;
 
 	/* Vehicles will wait at stations if they arrive early even if they are not
 	 * timetabled to wait there, so make sure the lateness counter is updated
diff -r e17a18bb827f src/timetable_gui.cpp
--- a/src/timetable_gui.cpp	Sat Oct 25 22:00:51 2008 +0000
+++ b/src/timetable_gui.cpp	Sun Oct 26 16:32:18 2008 +0100
@@ -301,9 +301,12 @@ struct TimetableWindow : Window {
 				DoCommandP(0, v->index, 0, NULL, CMD_SET_VEHICLE_ON_TIME | CMD_MSG(STR_CAN_T_TIMETABLE_VEHICLE));
 				break;
 
-			case TTV_AUTOFILL: /* Autofill the timetable. */
-				DoCommandP(0, v->index, HasBit(v->vehicle_flags, VF_AUTOFILL_TIMETABLE) ? 0 : 1, NULL, CMD_AUTOFILL_TIMETABLE | CMD_MSG(STR_CAN_T_TIMETABLE_VEHICLE));
-				break;
+			case TTV_AUTOFILL: { /* Autofill the timetable. */
+				uint32 p2 = 0;
+				if (!HasBit(v->vehicle_flags, VF_AUTOFILL_TIMETABLE)) SetBit(p2, 0);
+				if (_ctrl_pressed) SetBit(p2, 1);
+				DoCommandP(0, v->index, p2, NULL, CMD_AUTOFILL_TIMETABLE | CMD_MSG(STR_CAN_T_TIMETABLE_VEHICLE));
+			} break;
 		}
 
 		this->SetDirty();