All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger.
The Nisaab (the minimum amount liable for Zakah) of money is calculated according to gold and silver. It is what equals the amount of 85 grams of gold or 595 grams of silver. Besides, it is not an obligation for the company which you mentioned to pay Zakah on its equipments like cars nor on its building; rather, Zakah must be paid on its income if it reaches the Nisaab and a whole lunar year elapses over it.
However, if the company is owned by many people and not by one person, then Zakah is not due on its entire income; rather, Zakah must be paid according to the share of each partner separately if his share reaches the Nisaab by itself or by adding it to the other money or tradable item that he owns provided a whole lunar year elapses over it.
Allaah Knows best.