The carriage started slowly, then sped away.
The carriage moved quickly, but inside it was not bumpy.
Streets of this era were paved with stone slabs, uneven, with household waste and animal dung everywhere.
Some people even maliciously speculate that the nobility walk on tiptoe, carefully holding the hem of their skirts to avoid stepping on dirty things.
This view is widely accepted.
The reason for the carriage's smooth ride is the magic array beneath the compartment.
The highest-level magic array must balance stability, temperature control, cushioning, power, and even defense functions.
A large part of the cost of high-grade carriages lies in their magic arrays.
The stony resources of Theia Plane were exhausted in previous eras, declaring the end of the internal combustion era before it began. Magic civilization also sank along with the Magic Empire Creation Tower in the pre-magic era.