Hi nav..
As you're just starting out for now, it might be easier to grab a copy of the free brazil version available from Splutterfish's web site and then do a web search for 'bigrender' (free too). That'll enable you to use my scenes without having to mess about (yet) and be able to render large images via bigrender. At least you'd be able to get some results quickly.. then you can spend some time learning and changing things like the materials to use whatever renderer you like
I think most people here doing renders started that way.. now many just use my scenes as a base and modify the hell out of them to create much better / more interesting scenes for themselves.. I do too
If you do want to change materials.. hit the 'M' key to open the material editor window and select the relative material ball for the car. You should see a list of material slots. Click on each one in turn and just under the balls to the right, you'll see the 'Brazil Mtl' Davo mentions. Click on that and you'll see a long list of material types.. select 'Standard' from the list. Now you'll need to load the texture again by clicking the small empty square button next to the 'Diffuse' colour.. adjust the specular / glossiness values etc to get the look you want.
There's no right / wrong settings per-se so I can't give you a 'click this, change that to 100, make this grey' etc instructions.. but hope the above is useful anyway and always remember this takes time.. I've now been doing it for a couple of years now on and off and still nowhere near as good as some.
Regards,
Ian