[MTrenk]

A few points:
--> Spoilers are for good looks, or downforce. Recently someone developed an awful looking spoiler for vans that does crazy things to the flow behind the van resulting in highly decreased drag. Spoilers can be used correctly for lift, downforce, or drag reduction.
--> VG's are awesome and I followed Mitsubishi on that development as well. It's an effective solution, and that article is quite detailed, so if you're going for a trial and error process, they give you a fantastic set of conditions to start with! However, notice their tests are in line with what I've been saying: hours and hours of wind tunnel testing AND CFD. So good luck lol.
--> Best eco cars out there are just a bunch of airfoils connected together to protect the parts and driver of the car. Airfoil shapes win everytime.