Writing url with only the last category

[streetracershop]

I want to change the file route.php to get in the url only the last category
At this time rewriting gives me the following link:
http://www.streetracershop.com/auto/cerchi-in-lega/cerchi-in-lega-replica/cerchi-in-lega-replica-fiat/cerchi-in-lega-replica-fiat-da-15.html
I would like to get a link like the following:
http://www.streetracershop.com/cerchi-in-lega-replica-fiat/cerchi-in-lega-replica-fiat-da-15.html
What should I change in route.php?
And if I want to add also the manufacturer in the url?
I do not want to use components and plugins, I would like to have the website as much light as possible.
thank you

Joomla! 2.5.16
Virtuemart 2.0.24b
PHP 5.3.3

[Maxim Pishnyak]

Create a hidden menu item for each last category.