[megablast]

Exactly, it is just different shaped molds.

[onion2k]

For steel maybe, but even then it can be tricky to make some shapes. Doing it at scale with high precision is hard regardless of what you're making.

Bending more exotic metals, glass, and carbon fibre in more than one direction at once while maintaining it's strength is a really hard problem.

[sjwright]

Also less expensive car shapes are optimized for other priorities like space efficiency and ease of manufacture.

And don’t forget that much of what makes a sports car attractive is psychological and powered by a true perception of scarcity. If everyone’s car looked like an Aston Martin DB11 they wouldn’t be nearly so attractive as they look to us.