diff --git a/src/build_vehicle_gui.cpp b/src/build_vehicle_gui.cpp
index 32f26ef8ed..e8c7350183 100644
--- a/src/build_vehicle_gui.cpp
+++ b/src/build_vehicle_gui.cpp
@@ -1425,6 +1425,54 @@ struct BuildVehicleWindowBase : Window {
 
 		return list;
 	}
+
+	void FillTestedEngineCapacity(EngineID engine, CargoID cargo, TestedEngineDetails &te) const
+	{
+		const Engine *e = Engine::Get(engine);
+		if (!e->CanPossiblyCarryCargo()) {
+			te.cost = 0;
+			te.cargo = INVALID_CARGO;
+			te.all_capacities.Clear();
+			return;
+		}
+
+		if (this->virtual_train_mode) {
+			if (cargo != INVALID_CARGO && cargo != e->GetDefaultCargoType()) {
+				SavedRandomSeeds saved_seeds;
+				SaveRandomSeeds(&saved_seeds);
+				StringID err;
+				Train *t = BuildVirtualRailVehicle(engine, err, 0, false);
+				if (t != nullptr) {
+					const CommandCost ret = CmdRefitVehicle(0, DC_QUERY_COST, t->index, cargo | (1 << 16), nullptr);
+					te.cost          = ret.GetCost();
+					te.capacity      = _returned_refit_capacity;
+					te.mail_capacity = _returned_mail_refit_capacity;
+					te.cargo         = (cargo == INVALID_CARGO) ? e->GetDefaultCargoType() : cargo;
+					te.all_capacities = _returned_vehicle_capacities;
+					delete t;
+					RestoreRandomSeeds(saved_seeds);
+					return;
+				} else {
+					RestoreRandomSeeds(saved_seeds);
+				}
+			}
+		} else if (!this->listview_mode) {
+			/* Query for cost and refitted capacity */
+			CommandCost ret = DoCommand(this->window_number, engine | (cargo << 24), 0, DC_QUERY_COST, GetCmdBuildVeh(this->vehicle_type), nullptr);
+			if (ret.Succeeded()) {
+				te.cost          = ret.GetCost() - e->GetCost();
+				te.capacity      = _returned_refit_capacity;
+				te.mail_capacity = _returned_mail_refit_capacity;
+				te.cargo         = (cargo == INVALID_CARGO) ? e->GetDefaultCargoType() : cargo;
+				te.all_capacities = _returned_vehicle_capacities;
+				return;
+			}
+		}
+
+		/* Purchase test was not possible or failed, fill in the defaults instead. */
+		te = {};
+		te.FillDefaultCapacities(e);
+	}
 };
 
 /** GUI for building vehicles. */
@@ -1579,50 +1627,7 @@ struct BuildVehicleWindow : BuildVehicleWindowBase {
 
 		if (this->sel_engine == INVALID_ENGINE) return;
 
-		const Engine *e = Engine::Get(this->sel_engine);
-		if (!e->CanPossiblyCarryCargo()) {
-			this->te.cost = 0;
-			this->te.cargo = INVALID_CARGO;
-			this->te.all_capacities.Clear();
-			return;
-		}
-
-		if (this->virtual_train_mode) {
-			if (cargo != INVALID_CARGO && cargo != e->GetDefaultCargoType()) {
-				SavedRandomSeeds saved_seeds;
-				SaveRandomSeeds(&saved_seeds);
-				StringID err;
-				Train *t = BuildVirtualRailVehicle(this->sel_engine, err, 0, false);
-				if (t != nullptr) {
-					const CommandCost ret = CmdRefitVehicle(0, DC_QUERY_COST, t->index, cargo | (1 << 16), nullptr);
-					this->te.cost          = ret.GetCost();
-					this->te.capacity      = _returned_refit_capacity;
-					this->te.mail_capacity = _returned_mail_refit_capacity;
-					this->te.cargo         = (cargo == INVALID_CARGO) ? e->GetDefaultCargoType() : cargo;
-					this->te.all_capacities = _returned_vehicle_capacities;
-					delete t;
-					RestoreRandomSeeds(saved_seeds);
-					return;
-				} else {
-					RestoreRandomSeeds(saved_seeds);
-				}
-			}
-		} else if (!this->listview_mode) {
-			/* Query for cost and refitted capacity */
-			CommandCost ret = DoCommand(this->window_number, this->sel_engine | (cargo << 24), 0, DC_QUERY_COST, GetCmdBuildVeh(this->vehicle_type), nullptr);
-			if (ret.Succeeded()) {
-				this->te.cost          = ret.GetCost() - e->GetCost();
-				this->te.capacity      = _returned_refit_capacity;
-				this->te.mail_capacity = _returned_mail_refit_capacity;
-				this->te.cargo         = (cargo == INVALID_CARGO) ? e->GetDefaultCargoType() : cargo;
-				this->te.all_capacities = _returned_vehicle_capacities;
-				return;
-			}
-		}
-
-		/* Purchase test was not possible or failed, fill in the defaults instead. */
-		this->te = {};
-		this->te.FillDefaultCapacities(e);
+		this->FillTestedEngineCapacity(this->sel_engine, cargo, this->te);
 	}
 
 	void OnInit() override
@@ -2486,50 +2491,7 @@ struct BuildVehicleWindowTrainAdvanced final : BuildVehicleWindowBase {
 
 		if (state.sel_engine == INVALID_ENGINE) return;
 
-		const Engine *e = Engine::Get(state.sel_engine);
-		if (!e->CanPossiblyCarryCargo()) {
-			state.te.cost = 0;
-			state.te.cargo = INVALID_CARGO;
-			state.te.all_capacities.Clear();
-			return;
-		}
-
-		if (this->virtual_train_mode) {
-			if (cargo != INVALID_CARGO && cargo != e->GetDefaultCargoType()) {
-				SavedRandomSeeds saved_seeds;
-				SaveRandomSeeds(&saved_seeds);
-				StringID err;
-				Train *t = BuildVirtualRailVehicle(state.sel_engine, err, 0, false);
-				if (t != nullptr) {
-					const CommandCost ret = CmdRefitVehicle(0, DC_QUERY_COST, t->index, cargo | (1 << 16), nullptr);
-					state.te.cost          = ret.GetCost();
-					state.te.capacity      = _returned_refit_capacity;
-					state.te.mail_capacity = _returned_mail_refit_capacity;
-					state.te.cargo         = (cargo == INVALID_CARGO) ? e->GetDefaultCargoType() : cargo;
-					state.te.all_capacities = _returned_vehicle_capacities;
-					delete t;
-					RestoreRandomSeeds(saved_seeds);
-					return;
-				} else {
-					RestoreRandomSeeds(saved_seeds);
-				}
-			}
-		} else if (!this->listview_mode) {
-			/* Query for cost and refitted capacity */
-			const CommandCost ret = DoCommand(this->window_number, state.sel_engine | (cargo << 24), 0, DC_QUERY_COST, GetCmdBuildVeh(this->vehicle_type), nullptr);
-			if (ret.Succeeded()) {
-				state.te.cost          = ret.GetCost() - e->GetCost();
-				state.te.capacity      = _returned_refit_capacity;
-				state.te.mail_capacity = _returned_mail_refit_capacity;
-				state.te.cargo         = (cargo == INVALID_CARGO) ? e->GetDefaultCargoType() : cargo;
-				state.te.all_capacities = _returned_vehicle_capacities;
-				return;
-			}
-		}
-
-		/* Purchase test was not possible or failed, fill in the defaults instead. */
-		state.te = {};
-		state.te.FillDefaultCapacities(e);
+		this->FillTestedEngineCapacity(state.sel_engine, cargo, state.te);
 	}
 
 	void SelectColumn(bool wagon)