Removing $id from url with .htaccess - php

Question

I am using an .htaccess file to redirect "http://www.domain.com/cars/cars.php?cars_item=231" to "http://www.domain.com/cars/231/porsche"
So basically I'm redirecting 'cars.php?cars_item=231' to '$id/$title'
The .htaccess file consists of:
#Start
Options +FollowSymLinks -MultiViews
RewriteEngine On
RewriteBase /
# Redirect cars.php?cars_item=231 to cars/231/
RewriteCond %{THE_REQUEST} ^[A-Z]{3,}\s/+cars/cars\.php\?cars_item=([^&\s]+) [NC]
RewriteRule ^ /cars/%1 [R=302,L]
# Internally forward cars/231/ to cars.php?cars_item=231
RewriteRule ^cars/([0-9]+) /cars/cars.php?cars_item=$1 [NC,L,QSA]
#end
Then i'm using the following hrefs:
"http://domain.com/index.php" = echo porsche;
and in "http://www.domain.com/cars/cars.php" i'm using a $_GET['cars_item'];
My question is: How could I remove the $id from the url please? I want to have the following url as a result - "http://www.domain.com/cars/porsche" ... so basically I want to update the .htaccess and redirect "http://www.domain.com/cars/cars.php?cars_item=231" to "http://www.domain.com/cars/porsche"
This is because the $id in the url is creating some problems for indexing especially. Google keeps crawling "http://www.domain.com/cars/$id/" where as the $id is not a folder but is a db row hence I'd like to remove the $id from the url.
I would appreciate your help as always.