The slant is at the correct angle. Although you need to make the white section longer. If you look at this (
http://peterskuce.fotopic.net/p50853293.html) photo and measure it by the Grills, yours is one grill too short, if you get what I mean.
The National Express logo needs to be larger as you can also see in that photo.
Other than that, look about right to me. Like the colour choice too, seems just right to me.