Solved

HTML code shows different value of car part Acceleration then car part value on Car design page.

On my Cars/Overview page i see Acceleration = X, after pressing button Upgrade i see Acceleration on Car design page = X too.
But if i press review button and inspect progress bar HTML code i see X+1 there.
Is it a bug? What is real value? X or X+1? If real value = X, then why i see X+1 in HTML code?

I used to ask this. The +1 is the staff bonus I believe it is related to the Technical Director.

Well, my TD has no +1/-1. My CD has +1/-1. But +1 is not on Acceleration.

Interesting. There is a staff bonus?