Solved

spare parts

How many spare parts produces the production headquarters in the various upgrade levels?

If I read your question correct then every time you upgrade Manufacturing in Headquarters it gives you another part after every race. 
So for example my Manufacturing plant is at level 15. So after every race I receive 15 parts till I reach the maximum amount for that level. A level 12 Manufacturing plant would give you 12 spare parts after each race.

thank you Ian Mason