[MTrenk]

lol, I'm just trying to urge you to seek out more education on the subject of aerodynamics.

Having an angle greater on top than on bottom will cause lift. Lift is not good on cars in general, and lift creates drag just as much as downforce does. I choose downforce, it likely won't get me killed as easily in crosswinds.

It is more efficient to keep all curves smooth, especially when no one here is going to do a CFD analysis of this design. Airfoils are curved. I would recommend we look at successful aero projects (i.e. NASA, Boeing, extreme eco cars, top speed record cars) and see how many hard edges to an arbitrary angle we see. Yes you can do tricks with hard edges, but you probably don't know how to do that unless you are a physicist, mechanical, aerospace, or computational engineering, or a really bored homeschooled kid.

How do you suggest someone be 'safe' about the potential disturbances of having a hard angle downward at 20 degrees behind the car?

Hopefully you read that question and realize that your 'opinions' on how aerodynamics work are not helpful, and could potentially be hurtful to those who also don't know anything about aerodynamics.

However you are completely right about the smaller back. Kammback = chopped airfoil.
The closer you are to an airfoil shape, the more efficient you are. Not an opinion, a well researched theory that has plenty of evidence (not a fact/proven, just well evidenced).

However at '25 degrees you are pretty much guaranteed the flow won't reattach,' your opinion is meaningless. I guess you haven't studied how car designers manipulate the different types of flow at the boundary layer: laminate and turbulent. This is where those hard line and vortex generators come into play, designed by people with engineering degrees and hundreds of hours of experience in CFD and wind tunnel research. Neither you nor I are capable of creating these effects reliably, but I'm planning on gaining this skill in the future, and actively pursuing knowledge on these skills.

I could go on forever and ever, but my point is not to say you are wrong. The point is that you are providing incorrect information that could potentially lead to a poor design that might in fact harm mpg for Steve's Neon. Pretty sure all Chaz cares about is proving you wrong. All I want to do is encourage you to increase your education, or stop spreading your black magic 'opinions' on how you've decided aerodynamics work without doing any testing of your own.

As far as the building thing goes, I'm the Project Manager for my school's Formula SAE team. We design and build our cars from scratch. If anyone shares your sentiment about building something, it's me. There's nothing like seeing a vehicle you helped design come to life, built by your own hands. In the competition there is a fuel economy section, so you have to balance speed and economy to get the highest points.

Right now my life is centered around learning about vehicle dynamics, and I joined these forums because I know that I can help people learn amazing knowledge that will help them achieve their dreams, like I'm doing right now with no money, no car, but thirst for knowledge. I don't have an ego. I can fit all of my belongings in one of those fold up cubbies you hang in your closet that act as shelves. lol