Is zakat obligatory on a sum of money that has reached the nisab, but was paid to reserve a car that has not yet been received, and this was several months before the nisab was due?

If the money was paid as the price for a car intended for trade, its value is subject to zakat (definition) upon the completion of a hawl (lunar year) if the debtor is solvent and willing to pay. However, if the debtor is insolvent or procrastinates, zakat is not due until the money is received, and then it is paid for one year only. If the money was paid as a pledge or down payment, it remains under your ownership and is subject to zakat upon the completion of its hawl.