First of all, I'd like to say how much I love your work. And while I'm on the subject, how do you do the uv mapping on your models?
And onto the sprites! Personally, I think that the angle is fine, and the saturation is a bit over saturated. If this was a gba mockup, or a copy of the Advanced Wars colour then that would be fine. So, I think that you can get away with desaturating the colours a bit on the vehicles. Other than that, awsome job!