All the cars where built after the edit to the car design took place (for certain).
After much more playing, and researching everything in the tech tree and putting in place all the upgraded expanded slots, all the accessories are fitted.
I think I was expecting the basic starting slots to be upgradable as the expanded slots are. The Electonics slot is upgradable and I was expecting the Accessories slot to be upgradable too.
I find it odd that the basic “add accessories” slot doesn’t actually add any accessories from the tech tree and this was the problem I was having in my original picture above. This is detrimental at the start of a game when you need to be able to produce cars with accessories to make them more appealling and in order to make cash to afford the expanded slots.
This seems to be highly restrictive and don’t know if this a feature or a bug now