diff --git a/train_cmd.c b/train_cmd.c
--- a/train_cmd.c
+++ b/train_cmd.c
@@ -1318,10 +1318,6 @@ int32 CmdRefitRailVehicle(int x, int y, 
 	cost = 0;
 	num = 0;
 
-	// newgrf stuff can change graphics when refitting
-	if (!(flags & DC_EXEC))
-		InvalidateWindow(WC_VEHICLE_DEPOT, v->tile);
-
 	do {
 		/* XXX: We also refit all the attached wagons en-masse if they
 		 * can be refitted. This is how TTDPatch does it.  TODO: Have
@@ -1330,30 +1326,42 @@ int32 CmdRefitRailVehicle(int x, int y, 
 
 		if (v->cargo_cap != 0) {
 			RailVehicleInfo *rvi = RailVehInfo(v->engine_type);
-			uint16 amount = rvi->capacity;
-			CargoID old_cid = rvi->cargo_type;
-
-			/* the capacity depends on the cargo type, a rail vehicle
-			 * can carry twice as much mail/goods as normal cargo,
-			 * and four times as much passengers */
-			(old_cid == CT_PASSENGERS) ||
-			(amount <<= 1, old_cid == CT_MAIL || old_cid == CT_GOODS) ||
-			(amount <<= 1, true);
-			(new_cid == CT_PASSENGERS) ||
-			(amount >>= 1, new_cid == CT_MAIL || new_cid == CT_GOODS) ||
-			(amount >>= 1, true);
-
-			if (new_cid != v->cargo_type)
-				cost += (_price.build_railvehicle >> 8);
-			num += amount;
-			if (flags & DC_EXEC) {
-				//autorefitted train cars wants to keep the cargo
-				//it will be checked if the cargo is valid in CmdReplaceVehicle
-				if (!(SkipStoppedInDepotCheck))
-					v->cargo_count = 0;
-				v->cargo_type = new_cid;
-				v->cargo_cap = amount;
-				InvalidateWindow(WC_VEHICLE_DETAILS, v->index);
+			uint16 amount;
+			CargoID temp_cid = v->cargo_type;
+
+			/* Check the 'refit capacity' callback */
+			v->cargo_type = new_cid;
+			amount = GetCallBackResult(CB_REFIT_CAP, v->engine_type, v);
+			v->cargo_type = temp_cid;
+
+			if (amount == CALLBACK_FAILED) { // callback failed, use default
+				CargoID old_cid = rvi->cargo_type;
+				/* normally, the capacity depends on the cargo type, a rail vehicle
+				* can carry twice as much mail/goods as normal cargo,
+				* and four times as much passengers */
+				amount = rvi->capacity;
+				(old_cid == CT_PASSENGERS) ||
+				(amount <<= 1, old_cid == CT_MAIL || old_cid == CT_GOODS) ||
+				(amount <<= 1, true);
+				(new_cid == CT_PASSENGERS) ||
+				(amount >>= 1, new_cid == CT_MAIL || new_cid == CT_GOODS) ||
+				(amount >>= 1, true);
+			};
+
+			if (amount != 0) {
+				if (new_cid != v->cargo_type)
+					cost += (_price.build_railvehicle >> 8);
+				num += amount;
+				if (flags & DC_EXEC) {
+					//autorefitted train cars wants to keep the cargo
+					//it will be checked if the cargo is valid in CmdReplaceVehicle
+					if (!(SkipStoppedInDepotCheck))
+						v->cargo_count = 0;
+					v->cargo_type = new_cid;
+					v->cargo_cap = amount;
+					InvalidateWindow(WC_VEHICLE_DETAILS, v->index);
+					InvalidateWindow(WC_VEHICLE_DEPOT, v->tile);
+				}
 			}
 		}
 	// SkipStoppedInDepotCheck is called by CmdReplace and it should only apply to the single car it is called for