“The interest rate will play a huge role in how you pay the car off. If you got a promotional zero-percent APR rate, then putting the extra money in savings and paying the rest of the loan off when you have the cash makes sense.
But if your interest rate is higher than your savings rate (which is highly likely), you should keep paying month to month. To accelerate this process, if you have a bit of extra cash each month, make a principal-only payment. This will lower the amount you owe, which will subsequently lower your overall interest paid into the loan.