default template for taxonomy name

i have been testing taxonomies. i use to handle my taxonomy files with either taxonomy.php or taxonomy-{taxonomy}.php or with taxonomy-{taxonomy}-{term}.php. For example:
http://localhost/cars/ford/
where ‘cars’ is taxonomy and ‘ford’ is the term. and i made it handle with taxonomy-cars.php with desired results.

but i am having difficulties trying to get a default template for taxonomy-name. For example:
http://localhost/cars/
in this case, index.php is handling this url, not by the taxonomy.php file. Anyone knows what template/file handles this ?