Some Sports cars and Pickups are only half their normal quality?

[becephalus]

Some Sports cars and Pickups are only half their normal quality? Others are fine? Not sure what is going on.

[Chris Koźmik]

Some car types can have different requirements for different stats which affect quality in a different degree.

Sports cars have higher requirements for speed. So, for example if you make a slow sedan it's not a problem, but if you make a slow sports car it's a big problem and quality will deteriorate drastically.

There are also various different factors not specific to the car type (like car design date, the year where ecology starts to matter, etc).