Solved

Engines

So, at the end of the last season of my league, I bought 25 engines by tokens. The refurnishing had 1 race to go.
After the first race of the new season, it seems to me that the refurnishing didn't take place though, because I only have 25 engines, while I should have much more... Could you double-check please?

Your engines get restocked to 20, so if you have 0 you get 20, if you have 3 you get 17 more.
In case you have 20 or more engines they simply won't accumulate! That's why you don't buy engines before a restock

Ouch! Didn't know :P Thanks for explaining