You'll have to refresh your CollectionViewSource's View...so, in your handler for your combobox's SelectionChanged event, refresh your cvs:
cvsCars.View.Refresh();
You may want to look into the databinding powers of WPF and then later, the Model View ViewModel (MVVM) "pattern". That way, you can bind the combobox's SelectedItem
to a property on your window's DataContext
and eliminate the need for handling the SelectionChanged event.