Is zakat due on gold that has not been worn for years, and how is it calculated if due? And is zakat due on a car bought with the intention of selling it when needed or for profit, and how is its zakat calculated?

There is no Zakat (definition) on a car designated for personal use, even if you intend to sell it when needed. As for gold prepared for savings, or for spending when needed, or for hoarding and possession, Zakat is obligatory on it. Similarly, Zakat is obligatory on gold prepared for unforeseen circumstances (emergencies), even if it belongs to a woman. The Zakat on this gold must be paid for every year that passes while it is saved, at a rate of a quarter of a tenth (2.5%).