# Does GDP Income Approach hold?

Let me introduce my question with an example. There is a company producing cars. $$20$$ cars are produced, with a value market of $$20000u$$. $$\textrm{GDP} = 20\cdot20000u = 400000u$$. Assume that the company doesn't purchase any intermediate good, so all the income, $$400000u$$ goes for the company, and you can compute (income approach) $$\textrm{GDP} = \textrm{S} + \textrm{B}$$, where $$\textrm{S}$$ stands for salaries and $$\textrm{B}$$ for benefit. But we are somehow assuming that the company will get $$400000u$$ for selling the cars. What would happen if they only sell 15 cars? They will only get $$15\cdot20000u = 300000u$$, so $$\textrm{S} + \textrm{B} \neq \textrm{GDP}$$. I have read that this is written down as if the company buys the $$5$$ remaining cars, but there is no money transfer here, so they can't distribute the $$100000u$$ worth of cars between $$\textrm{S}$$ and $$\textrm{B}$$. Why would the income approach for GDP hold in general?