// обработка нажатия кнопки добавления
private async void CreateCar(object sender, EventArgs e)
{
Car friend = new Car();
CarPage friendPage = new CarPage();
friendPage.BindingContext = friend;
await Navigation.PushAsync(friendPage);
}
// обработка нажатия элемента в списке
private async void OnItemSelected(object sender, SelectedItemChangedEventArgs e)
{
Car selectedCar = (Car)e.SelectedItem;
CarPage carPage = new CarPage();
carPage.BindingContext = selectedCar;
await Navigation.PushAsync(carPage);
}