why category__and and category__in wont work togather?

You need a query like this –

$args = array(
    'post_type' => 'post',
    'tax_query' => array(
        'relation' => 'AND',
        array(
            'taxonomy' => 'category',
            'field' => 'slug',
            'terms' => array( 'car', 'truck', 'bus' ),
            'operator' => 'IN'
        ),
        array(
            'taxonomy' => 'category',
            'field' => 'name',
            'terms' => 'Toronto'
        )
    )
);