Check if php insert was successful when using AngularJS $http

I'm a beginner when it comes to AngularJS but I have just figured out how to pass POST data using the $http service to a PHP file to insert to my database.

This is my add.php file. It displays my form and has the insert code block at the bottom:

<h2>Add Car</h2>
<div ng-controller="formCtrl">
    <form method="POST">
        <label>Make:</label>
        <select ng-model="car.make">
            <option>Make 1</option>
            <option>Make 2</option>
            <option>Make 3</option>
        </select>
        <label>Model:</label>
        <input type="text" ng-model="car.model">
        <input type="submit" ng-click="addCar(car)">
    </form>

    <pre>
        {{message}}
    </pre>
</div>


<?php
$data = json_decode(file_get_contents("php://input"));
$make = $data->make;
$model = $data->model;

$con = new PDO('mysql:host=localhost;dbname=mydb', 'user', 'pass');

$stmt = $con->prepare("INSERT INTO cars (model, make) VALUES(?, ?)");
$stmt->bindParam(1, $model);
$stmt->bindParam(2, $make);
$stmt->execute();
?>

This is my controller:

app.controller('formCtrl', function ($scope, $http) {

    $scope.addCar = function (car) {

        $http({
            method: 'POST',
            url: 'tools/add.php',
            data: car,
            headers: {'Content-Type': 'application/x-www-form-urlencoded'},
        })
        .then(function (response) {
           $scope.message = "great!"; 
        });
    }
});

Now is there anyway to check to see if the insert was successful? I know you can use the rowCount() function to check on the PHP side and then set your message to either be an error or a successful insert, but I'd like to know if there's anyway for my JS to know whether a row was actually inserted or not.