Welcome, rc1, it's nice that you chose pak192.comic as your playground.
To be able to show you exactly what's "wrong", I attached an image. It's your train, but I pixeled over it. It's not intended to be finished like that, just a quick job to show you what we understand as a Comic graphic. Of course more details and better Anti-Aliasing is allowed, but "blur" is bad. It's best to restrict yourself to a palette of about 6-8 shades per color. This helps defining a crisp image and allows easy conversion to player color.
That being said, I doubt your train is pixeled in the first place, it looks more like it is rendered. I don't think there is much you can do about it, except pixeling over the whole thing like I did after rendering.
I don't agree with an_dz about the colors, they are fine with me. But since it's blue and yellow, I'd definitly use player colors.