I’m surprised I couldn’t find this suggestion despite having searched for it. Maybe it’s because I used leo.org to translate from german “Abrisskante” and neither break-away edge nor tear-off edge is the correct translation, so if it’s been suggested already please forgive me.
So I tried to make break-away edges at the top-rear part of my cars by placeing lips, but they usually stand out upwards instead of backwards and even if not, they don’t exactly look like they should. I’d therefore like to suggest them as additional fixture.
These edges are meant to reduce drag at high speeds. This happens because at a certain speed the air can’t flow along the body anymore and therefore it breaks away, descending along a smooth line behind the car. The air behind the car then travels with the car becomeing kind of the rear part of the car. So the bigger the area between road and the edge, the more drag reduction. The less body behind the edge (or the steeper the rear part) and the more sharp and sticking out the egde is the less speed is necessary for this effect.
You can see these edges at many modern wagons, hatch-backs (at rear end of roof) and even some sedans (on trunk).
Note: Wings behind and below the edge would lose their effectiveness above break-away speed.
I’m not asking for a realistic implementation, but I’d like to have something and I find this feature to be more than just some tiny detail…
