Hello guys, I'm looking templates of every car, which are .png and so I can paint each part at once. I use Microsoft Paint & Powerpoint, and I'm not going to use GIMP, Paint.net or Photoshop. I just want to make skins simplest way as possible.

Here's MRT's template made by me, which took ages. I would really appreciate if you guys could help and save my time.
http://gametechmods.com/../uploads/images/65937MRT.png

At first I'll throw the clever advice - you should switch to something advanced,for sake of quality at least,as MSpaint saves jpg files at quite low quality,distorting colors. GIMP could be the best,as it's freeware.

But here are black mask templates (like yours) for all cars and helmet: link
These are made from black masks from Master Skinnerz skin kits.

PS. Either XFR or XRR (can't remember which) has mirror position wrong,as it was updated since latest skin kit update,check yourself using default skins from latest CMXviewer.

Only thing that bothers me is that when I paint it red for example, the edges stay white. Even though I should be fix it myself, so thankyou.

It's because of the anti-aliasing.

Even though you won't propably do this, but just get GIMP/PS, you won't get these problems and it is easier to work with layers.