The balance sheet of a company follows the fundamental accounting equation that states that assets equal liabilities plus shareholders' equity, and this is why a balance sheet actually balances.

We can present vehicles paid off on this equation like this (let say its value os $100,000

From this we can see that vehicles that have been paid off are balanced against shareholders' equity in the balance sheet.

You can also think about this conceptually like this:

For a company to have the cash to either purchase vehicles without incurring liabilities or to pay off a vehicle loan, it must either generate net income or get contributions from its shareholders, and both these sources are elements of shareholders' equity.