I like the design! My suggestion is to use the 2x3x1 window panels for the windshield to avoid all the crisscrossing lines. I would also suggest making the top level of the lightbar studless and adding doors on the body to give it some definition. I think something needs to be done to that right-side rear door, it looks weird the way you have it. The stripe is also too low, but just by one plate. The perimeter lighting is incorrect, as is the rear lighting and the ArrowStik. The perimeter lighting should be all RED, the ArrowStik should be YELLOW, and the rear lighting should comply with the standards on the website. Overall, it's a very nice rig! It just needs some work.
The only thing this is wrong is that the back light bar can only be 4 studs wide and all white or amber. how to get in is that you have to type medlink and pick any lego than go down the page and there is a box that said medlink and has a pic in it that will lead you to a diffent page it the top [under the mocpages toolbar] on the right there a botton that said join this group