On the Hotwheels skin, I'd recommend de-saturating the blue slightly. It looks horribly fake as is, which is a common problem on blue skins, and green skins. I'd darken it a little, too, but that is personal preference. I'd also change the number, that font doesn't fit the skin very well imho, and I think the stroke (or is it an outter glow? Sorry.. tired eyes, i need some sleep :P) is a little too thick for that particular font. I'd be inclined to go with something bolder, or something more streamlined if you want the thinner look. Also, the number and the Mobil 1 logo on the side are crossing the door-line. I'd make them just a touch smaller so they don't cross that line. Similarily, the ATI logo just bleeds onto the bottom-most out-step on the side. Lastly, it looks like the skin was made at 1024 resolution. I'd recommend you use 2048 res in the future; I'd also recommend Bunta's skin kits from Master Skinnerz
I know, lots of nitpicks, but I still love Hotwheels so skins featuring the brand get a lot of attention and inspection from me :P hehe.
The Crown Royal/Coke car is quite nice as well, the colour gradient was nicely done. The decal size and placement makes it look like a regional weekend club racer; and image perfect for that car.
All just small crits by me, both skins done quite nicely indeed!