How to properly use GET attributes

So it's really simple question, but i have to be sure that i make it in a right way 
I want to implement GET parameters for filtering
so i wanna get something like - mysite.com/cars/ford/?price_from=10&price_to=20
In this case - GET parameters are optional, and there could be a lot of them.
I don't want users to see PHP file. mysite.com/cars/ford/index.php?price_from=10&price_to=20 (or something like that)

So how do i properly implement this? I mean follow the codeigniter path

Just manually check native PHP - $_GET ?
And how do i setup route table?