How Have Large Vehicles Been Modified for Better Aerodynamics?

[lego indy]

Homework Statement

My physics teacher has set me this homework where I have to find out how large vehicles(lorries,trains,etc.) have been modified to be more aerodynamic. please could you just give me some links or pointers to help me finish this task.





2. The attempt at a solution
I have been searching around and have only found links to complicated aerodynamics like:
https://www.physicsforums.com/showthread.php?t=247602
http://www.accessscience.com/abstract.aspx?id=YB031110&referURL=http%3a%2f%2fwww.accessscience.com%2fcontent.aspx%3fid%3dYB031110
and
http://www.redwingengineering.com/vehicle_aero.html

 

[mgb_phys]

You could start with www.wisil.recumbents.com/car_aerodynamics/