diff --git a/TODO.md b/TODO.md
index e9238bc..62013ea 100644
--- a/TODO.md
+++ b/TODO.md
@@ -25,8 +25,8 @@
 ## What has to be done
 - [x] Vehicle delete
 - [ ] intro tutorial when no car exist or just dont show anything
-- [ ] change/set default car
-- [ ] hide errors
+- [x] change/set default car
+- [x] hide errors
 
 ## Nice to have
 - [ ] specific car view - charts, fuel records
diff --git a/app/controllers/VehicleController.php b/app/controllers/VehicleController.php
index 231e8dc..f5f7ede 100644
--- a/app/controllers/VehicleController.php
+++ b/app/controllers/VehicleController.php
@@ -75,6 +75,18 @@ class VehicleController extends Controller {
         $this->view('vehicles/index', ['title' => 'Vehicles', 'vehicles' => $vehicles]);
     }
 
+    public function setDefault() {
+        $vehicle = new Vehicle();
+        // TODO: Validate the request
+        $result = $vehicle->setDefaultVehicle($_POST['vehicle_id'], $_SESSION['user']['id']);
+        if($result != true) {
+            echo "Something went wrong";
+            return;
+        }
+
+        $this->view('vehicles/index', ['title' => 'Vehicles', 'vehicles' => $vehicles]);
+    }
+
     public function api_get() {
         if(!$_SERVER['REQUEST_METHOD'] === 'GET') {
             echo "Wrong method, use GET";
diff --git a/app/models/Vehicle.php b/app/models/Vehicle.php
index 6884c9f..c22349b 100644
--- a/app/models/Vehicle.php
+++ b/app/models/Vehicle.php
@@ -61,6 +61,39 @@ class Vehicle {
         return $result->fetch_assoc();
     }
 
+    public function setDefaultVehicle($vehicle_id, $user_id) {
+        try {
+            $this->db->begin_transaction();
+
+            $stmt = $this->db->prepare("
+                UPDATE `vehicles` 
+                SET `is_default` = 0 
+                WHERE `user_id` = ? AND `is_default` = 1
+            ");
+            $stmt->bind_param("i", $user_id);
+            $stmt->execute();
+            $stmt->close();
+
+            $stmt = $this->db->prepare("
+                UPDATE `vehicles` 
+                SET `is_default` = 1 
+                WHERE `id` = ? AND `user_id` = ?
+            ");
+            $stmt->bind_param("ii", $vehicle_id, $user_id);
+
+            if ($stmt->execute()) {
+                $this->db->commit();
+                return true;
+            } else {
+                $this->db->rollback();
+                return "Error: " . $stmt->error;
+            }
+        } catch (mysqli_sql_exception $e) {
+            $this->db->rollback();
+            return $e->getMessage();
+        }
+    }
+
     public function delete($vehicle_id, $user_id) {
         try {
             $stmt = $this->db->prepare("SELECT id FROM vehicles WHERE id = ? AND user_id = ?");
diff --git a/app/views/vehicles/index.php b/app/views/vehicles/index.php
index 7d86f3a..3d04b15 100644
--- a/app/views/vehicles/index.php
+++ b/app/views/vehicles/index.php
@@ -14,10 +14,15 @@
                 <p><?= htmlspecialchars($vehicle['fuel_type']) ?></p>
                 <p><?= htmlspecialchars($vehicle['note'] ?? "") ?></p>
                 <div class="actions">
-                <form method="POST" action="/vehicles/delete">
-                    <input type="number" name="vehicle_id" value="<?= $vehicle['id'] ?>" style="display: none">
-                    <input type="submit" value="Delete vehicle" class="btn-danger">
-                </form>
+                    <form method="POST" action="/vehicles/delete">
+                        <input type="number" name="vehicle_id" value="<?= $vehicle['id'] ?>" style="display: none">
+                        <input type="submit" value="Delete vehicle" class="btn-danger">
+                    </form>
+
+                    <form method="POST" action="/vehicles/default">
+                        <input type="number" name="vehicle_id" value="<?= $vehicle['id'] ?>" style="display: none">
+                        <input type="submit" value="Set default" class="btn-primary">
+                    </form>
                 </div>
             </div>
         <?php endforeach; ?>
diff --git a/public/index.php b/public/index.php
index 2159595..4a103e0 100644
--- a/public/index.php
+++ b/public/index.php
@@ -47,6 +47,7 @@ $router->group('/vehicles', ['RequireAuth'], function ($router) {
     $router->add('/create', 'VehicleController@create');
     $router->add('/edit/{id}', 'VehicleController@edit');
     $router->add('/delete', 'VehicleController@delete');
+    $router->add('/default', 'VehicleController@setDefault');
 });
 
 $router->group('/refuel', ['RequireAuth'], function ($router) {