diff --git a/src/group_cmd.cpp b/src/group_cmd.cpp
index 9a19090a2..7d29b4f84 100644
--- a/src/group_cmd.cpp
+++ b/src/group_cmd.cpp
@@ -173,7 +173,13 @@ void GroupStatistics::Clear()
 {
 	assert(delta == 1 || delta == -1);
 	GroupStatistics::GetAllGroup(v).num_engines[v->engine_type] += delta;
-	GroupStatistics::Get(v).num_engines[v->engine_type] += delta;
+	if (IsDefaultGroupID(v->group_id)) {
+		GroupStatistics::Get(v).num_engines[v->engine_type] += delta;
+	} else {
+		for (Group *g = Group::Get(v->group_id); g != NULL; g = Group::GetIfValid(g->parent)) {
+			g->statistics.num_engines[v->engine_type] += delta;
+		}
+	}
 }
 
 /**
@@ -265,10 +271,22 @@ static inline void UpdateNumEngineGroup(const Vehicle *v, GroupID old_g, GroupID
 {
 	if (old_g != new_g) {
 		/* Decrease the num engines in the old group */
-		GroupStatistics::Get(v->owner, old_g, v->type).num_engines[v->engine_type]--;
+		if (IsDefaultGroupID(old_g)) {
+			GroupStatistics::Get(v->owner, old_g, v->type).num_engines[v->engine_type]--;
+		} else {
+			for (Group *g = Group::Get(old_g); g != NULL; g = Group::GetIfValid(g->parent)) {
+				g->statistics.num_engines[v->engine_type]--;
+			}
+		}
 
 		/* Increase the num engines in the new group */
-		GroupStatistics::Get(v->owner, new_g, v->type).num_engines[v->engine_type]++;
+		if (IsDefaultGroupID(old_g)) {
+			GroupStatistics::Get(v->owner, new_g, v->type).num_engines[v->engine_type]++;
+		} else {
+			for (Group *g = Group::Get(new_g); g != NULL; g = Group::GetIfValid(g->parent)) {
+				g->statistics.num_engines[v->engine_type]++;
+			}
+		}
 	}
 }
 
@@ -432,6 +450,11 @@ CommandCost CmdAlterGroup(TileIndex tile, DoCommandFlag flags, uint32 p1, uint32
 				g2->statistics.num_vehicle -= g->statistics.num_vehicle;
 				g2->statistics.num_profit_vehicle -= g->statistics.num_profit_vehicle;
 				g2->statistics.profit_last_year -= g->statistics.profit_last_year;
+
+				Engine *e;
+				FOR_ALL_ENGINES(e) {
+					g2->statistics.num_engines[e->index] -= g->statistics.num_engines[e->index];
+				}
 			}
 
 			g->parent = (pg == NULL) ? INVALID_GROUP : pg->index;
@@ -440,6 +463,11 @@ CommandCost CmdAlterGroup(TileIndex tile, DoCommandFlag flags, uint32 p1, uint32
 				g2->statistics.num_vehicle += g->statistics.num_vehicle;
 				g2->statistics.num_profit_vehicle += g->statistics.num_profit_vehicle;
 				g2->statistics.profit_last_year += g->statistics.profit_last_year;
+
+				Engine *e;
+				FOR_ALL_ENGINES(e) {
+					g2->statistics.num_engines[e->index] += g->statistics.num_engines[e->index];
+				}
 			}
 		}
 	}
@@ -724,13 +752,8 @@ void UpdateTrainGroupID(Train *v)
  */
 uint GetGroupNumEngines(CompanyID company, GroupID id_g, EngineID id_e)
 {
-	uint count = 0;
 	const Engine *e = Engine::Get(id_e);
-	const Group *g;
-	FOR_ALL_GROUPS(g) {
-		if (g->parent == id_g) count += GetGroupNumEngines(company, g->index, id_e);
-	}
-	return count + GroupStatistics::Get(company, id_g, e->type).num_engines[id_e];
+	return GroupStatistics::Get(company, id_g, e->type).num_engines[id_e];
 }
 
 void RemoveAllGroupsForCompany(const CompanyID company)