diff --git a/src/ai/api/ai_vehicle.cpp b/src/ai/api/ai_vehicle.cpp
--- a/src/ai/api/ai_vehicle.cpp
+++ b/src/ai/api/ai_vehicle.cpp
@@ -49,13 +49,7 @@
 
 	const Vehicle *v = ::Vehicle::Get(vehicle_id);
 	switch (v->type) {
-		case VEH_ROAD: {
-			uint total_length = 0;
-			for (const Vehicle *u = v; u != NULL; u = u->Next()) {
-				total_length += ::RoadVehicle::From(u)->rcache.cached_veh_length;
-			}
-			return total_length;
-		}
+		case VEH_ROAD:  return ::RoadVehicle::From(v)->rcache.cached_total_length;
 		case VEH_TRAIN: return ::Train::From(v)->tcache.cached_total_length;
 		default: return -1;
 	}
diff --git a/src/vehicle_gui.cpp b/src/vehicle_gui.cpp
--- a/src/vehicle_gui.cpp
+++ b/src/vehicle_gui.cpp
@@ -854,9 +854,7 @@ static int CDECL VehicleLengthSorter(con
 			break;
 
 		case VEH_ROAD: {
-			const RoadVehicle *u;
-			for (u = RoadVehicle::From(*a); u != NULL; u = u->Next()) r += u->rcache.cached_veh_length;
-			for (u = RoadVehicle::From(*b); u != NULL; u = u->Next()) r -= u->rcache.cached_veh_length;
+			r = RoadVehicle::From(*a)->rcache.cached_total_length - RoadVehicle::From(*b)->rcache.cached_total_length;
 			break;
 		}