Comment by AlotOfReading

I assume you mean the line near the handles on this Corolla [1]? That whole part of the car is doing a lot of different things.

1. Flat vertical panels are a no-no. Adding creases increases buckling resistance.

2. That's a hugely important area for cabin noise because the side mirrors cause turbulence and the vehicle body needs a channel to constrain the turbulent flow and flex as little as possible near the door seals.

3. The skin needs to expand outwards from the line of the pillars to fit the window mechanisms, the handles/locks, and the side impact protection without intruding into the cabin space.

4. It makes the car look more sporty and interesting. The technical term for the crease itself is "character line", and it's the main reason why the Corolla has one. It's visual reinforcement for the modern standard combo of low hoods-high trunks that's considered attractive styling.

5. The greenhouse (cabin) narrows towards the top for rollover safety and aerodynamic reasons (a.k.a tumblehome), and this needs to blend with the rest of the body in a visually appealing way. The cybertruck is a good example of how unusual it can look if this is just a straight line on the body. Here's a comparison between the current design and an ai-generated "rounded" design [2] [3].

[1] https://file.kelleybluebookimages.com/kbb/base/evox/CP/44005...

[2] https://www.motortrend.com/files/67a2770e2906d20008bad29f/1-...

[3] https://static0.carbuzzimages.com/wordpress/wp-content/uploa...