Wow you went all out on your photo-manipulation assignment! It looks impressive! I'd like to suggest a couple of things though, if you don't mind?
1- to add a hue/ colour/ saturation layer (or a couple) over the entire thing (near the end of the teaching video where he makes one himself, Marc shows you how to do so) to really bring it all together?
2- check your light source(s), the building is strongly lit from the left, but the motor rider appears to be lit from the right. Try finding one spot you want your light to come from and possibly some resources that have a similar light source. You can also use the burn and dodge tools to help deepen and lighten areas (as well as various other colour editing settings Marc uses in his video) but it takes a little practice to use these tools c: