This is where I would say you need to start looking at what you want, and how important a car is for you.
The reason I ask is because over 6 years, a substantial amount of what you pay will be interest. By going with a shorter repayment period, you could save yourself a LOT of money. However, that may require a cheaper car, or a larger deposit, which might mean you would either have to look for longer, or save for longer, or both.
My brother constructed a spreadsheet that would calculate how much, in total, you would pay the bank, and how much of that is interest. Over periods of 5 years and over, very quickly you end up paying half the value of your car in interest.
Thats why I suggest thinking long and hard before getting into debt for 6 years. You might love your car now, but what about 6 years time? If you got a cheaper car now, you could pay it off quicker, pay less on interest, and then get a new car faster.
72 times R1686 is R121000. You pay the bank R30000 for borrowing their money to buy a car.
That being said, the other side of the coin is sometimes you NEED a car, and not everyone has R40k, or R90k, sitting in their back pocket for a car, so debt is practically unavoidable. And you might decide you like a R90k car now more than you like R30k at some point in the future. Up to you. But think about it carefully.