diff --git a/lib/feature/car_selection/bloc/bloc.dart b/lib/feature/car_selection/bloc/bloc.dart
index c027e32..b58d58e 100644
--- a/lib/feature/car_selection/bloc/bloc.dart
+++ b/lib/feature/car_selection/bloc/bloc.dart
@@ -2,7 +2,7 @@ import 'package:flutter/cupertino.dart';
 import 'package:flutter_bloc/flutter_bloc.dart';
 import 'package:hl_lieferservice/feature/car_selection/repository/car_selection_repository.dart';
 import 'package:hl_lieferservice/feature/cars/model/selection.dart';
-import 'package:hl_lieferservice/domain/entity/car.dart';
+import 'package:hl_lieferservice/domain/repository/cars_repository.dart';
 
 import 'events.dart';
 import 'state.dart';
@@ -10,7 +10,12 @@ import 'state.dart';
 class CarSelectBloc extends Bloc<CarSelectEvent, CarSelectState> {
   final CarSelectionRepository repository;
 
-  CarSelectBloc({required this.repository}) : super(CarSelectInitial()) {
+  /// Fahrzeuge des angemeldeten Accounts vom Server — gegen sie wird eine
+  /// gespeicherte Tagesauswahl geprüft.
+  final CarsRepository carsRepository;
+
+  CarSelectBloc({required this.repository, required this.carsRepository})
+    : super(CarSelectInitial()) {
     on<CarSelectLoad>(_load);
     on<CarSelectConfirm>(_confirm);
     on<CarSelectChange>(_change);
@@ -36,23 +41,21 @@ class CarSelectBloc extends Bloc<CarSelectEvent, CarSelectState> {
           stored.date.day == today.day;
 
       if (validForToday) {
-        emit(
-          CarSelectComplete(
-            selectedCar: Car(
-              id: stored.selectedCarId!,
-              // accountId/active fließen aus der lokalen Selection
-              // nicht durch — wir persistieren nur (id, plate) als
-              // UI-Pointer. Die Tour-Logik holt die vollständigen
-              // Car-Felder weiterhin aus dem CarsBloc-Listing.
-              accountId: 0,
-              plate: stored.selectedCarPlate!,
-              active: true,
-            ),
-          ),
-        );
-      } else {
-        emit(CarSelectRequired());
+        // Die lokale Auswahl ist nur ein Zeiger. Sie gilt nur, wenn das
+        // Fahrzeug laut Server (frisch geladen) zu diesem Account gehört
+        // und aktiv ist — sonst z. B. ein Fahrzeug eines anderen Fahrers,
+        // das auf diesem Gerät gewählt wurde.
+        final ownCars = await carsRepository.listMine();
+        final car = ownCars
+            .where((c) => c.id == stored.selectedCarId && c.active)
+            .firstOrNull;
+        if (car != null) {
+          emit(CarSelectComplete(selectedCar: car));
+          return;
+        }
+        await repository.clearSelection(event.userId);
       }
+      emit(CarSelectRequired());
     } catch (e, st) {
       debugPrint('CarSelectBloc._load failed: $e');
       debugPrint('Stacktrace: $st');
diff --git a/lib/feature/car_selection/repository/car_selection_repository.dart b/lib/feature/car_selection/repository/car_selection_repository.dart
index 2cc265e..650b30e 100644
--- a/lib/feature/car_selection/repository/car_selection_repository.dart
+++ b/lib/feature/car_selection/repository/car_selection_repository.dart
@@ -49,6 +49,15 @@ class CarSelectionRepository {
     );
   }
 
+  /// Verwirft die gespeicherte Auswahl (z. B. Fahrzeug gehört nicht mehr
+  /// zum Account) — der Fahrer muss neu wählen.
+  Future<void> clearSelection(String userId) async {
+    final prefs = await SharedPreferences.getInstance();
+    await prefs.remove(_keyDate(userId));
+    await prefs.remove(_keyCarId(userId));
+    await prefs.remove(_keyCarPlate(userId));
+  }
+
   Future<void> saveSelection(String userId, CarSelection selection) async {
     final prefs = await SharedPreferences.getInstance();
 
diff --git a/lib/widget/session_scope.dart b/lib/widget/session_scope.dart
index 9d89b05..df445e3 100644
--- a/lib/widget/session_scope.dart
+++ b/lib/widget/session_scope.dart
@@ -94,6 +94,7 @@ class _SessionScopeState extends State<SessionScope> {
               repository: CarSelectionRepository(
                 environmentId: widget.environmentId,
               ),
+              carsRepository: CarsRepositoryImpl(locator<HolzleitnerApi>()),
             ),
           ),
           BlocProvider(
diff --git a/test/car_selection_bloc_test.dart b/test/car_selection_bloc_test.dart
new file mode 100644
index 0000000..da2ad26
--- /dev/null
+++ b/test/car_selection_bloc_test.dart
@@ -0,0 +1,74 @@
+import 'package:flutter_test/flutter_test.dart';
+import 'package:shared_preferences/shared_preferences.dart';
+
+import 'package:hl_lieferservice/domain/entity/car.dart';
+import 'package:hl_lieferservice/domain/repository/cars_repository.dart';
+import 'package:hl_lieferservice/feature/car_selection/bloc/bloc.dart';
+import 'package:hl_lieferservice/feature/car_selection/bloc/events.dart';
+import 'package:hl_lieferservice/feature/car_selection/bloc/state.dart';
+import 'package:hl_lieferservice/feature/car_selection/repository/car_selection_repository.dart';
+
+/// Fahrzeuge „laut Server" für den angemeldeten Account.
+class _ServerCars implements CarsRepository {
+  _ServerCars(this.cars);
+  final List<Car> cars;
+
+  @override
+  Future<List<Car>> listMine({bool includeInactive = false}) async => cars;
+
+  @override
+  dynamic noSuchMethod(Invocation invocation) => super.noSuchMethod(invocation);
+}
+
+const _fremdesAuto = 'b918b721-0000-0000-0000-000000000423';
+
+Map<String, Object> _gespeichert(String userId, String carId) => {
+  'flutter.car_selection_test_${userId}_date': DateTime.now().toIso8601String(),
+  'flutter.car_selection_test_${userId}_car_id': carId,
+  'flutter.car_selection_test_${userId}_car_plate': 'test',
+};
+
+Future<CarSelectState> _laden(String userId, List<Car> serverCars) async {
+  final bloc = CarSelectBloc(
+    repository: CarSelectionRepository(environmentId: 'test'),
+    carsRepository: _ServerCars(serverCars),
+  )..add(CarSelectLoad(userId: userId));
+  final state = await bloc.stream.firstWhere(
+    (s) => s is! CarSelectLoading,
+  );
+  await bloc.close();
+  return state;
+}
+
+void main() {
+  TestWidgetsFlutterBinding.ensureInitialized();
+
+  test('gespeichertes Fahrzeug eines anderen Fahrers wird verworfen', () async {
+    // 414 hat auf diesem Gerät das Auto von 423 als Tagesfahrzeug gespeichert.
+    SharedPreferences.setMockInitialValues(_gespeichert('414', _fremdesAuto));
+
+    final state = await _laden('414', const []);
+
+    expect(state, isA<CarSelectRequired>());
+    final prefs = await SharedPreferences.getInstance();
+    expect(prefs.getString('car_selection_test_414_car_id'), isNull);
+  });
+
+  test('eigenes aktives Fahrzeug wird übernommen, mit Serverdaten', () async {
+    SharedPreferences.setMockInitialValues(_gespeichert('423', _fremdesAuto));
+    const auto = Car(id: _fremdesAuto, accountId: 423, plate: 'test', active: true);
+
+    final state = await _laden('423', const [auto]);
+
+    expect(state, isA<CarSelectComplete>());
+    expect((state as CarSelectComplete).selectedCar.accountId, 423);
+  });
+
+  test('deaktiviertes Fahrzeug gilt nicht mehr', () async {
+    SharedPreferences.setMockInitialValues(_gespeichert('423', _fremdesAuto));
+    const auto =
+        Car(id: _fremdesAuto, accountId: 423, plate: 'test', active: false);
+
+    expect(await _laden('423', const [auto]), isA<CarSelectRequired>());
+  });
+}
diff --git a/test/session_scope_test.dart b/test/session_scope_test.dart
index c86fa3e..236ae48 100644
--- a/test/session_scope_test.dart
+++ b/test/session_scope_test.dart
@@ -12,8 +12,10 @@ import 'package:hl_lieferservice/feature/authentication/bloc/auth_bloc.dart';
 import 'package:hl_lieferservice/feature/car_selection/bloc/bloc.dart';
 import 'package:hl_lieferservice/feature/delivery/bloc/tour_date_cubit.dart';
 import 'package:hl_lieferservice/feature/payment_methods/bloc/payment_methods_cubit.dart';
+import 'package:hl_lieferservice/main.dart' show locator;
 import 'package:hl_lieferservice/widget/operations/bloc/operation_bloc.dart';
 import 'package:hl_lieferservice/widget/session_scope.dart';
+import 'package:holzleitner_api/holzleitner_api.dart' show HolzleitnerApi;
 
 /// Token-Provider ohne Keycloak: der Test steuert Login/Logout über [emit].
 class _FakeTokenProvider implements KeycloakOidcTokenProvider {
@@ -45,6 +47,14 @@ AuthLoggedIn _login(int personalnummer) =>
     AuthLoggedIn({'personalnummer': personalnummer, 'name': 'Fahrer'});
 
 void main() {
+  // Session-Blocs bauen ihre Repositories gegen den API-Client; im Test
+  // reicht ein unbenutzter Client (es wird nichts geladen).
+  setUpAll(() {
+    if (!locator.isRegistered<HolzleitnerApi>()) {
+      locator.registerSingleton<HolzleitnerApi>(HolzleitnerApi());
+    }
+  });
+
   late _FakeTokenProvider provider;
   late _CountingPaymentMethods payments;
   late List<CarSelectBloc> carSelections;