A pre-approval is an offer in principle. The credit provider looks at what you earn, what you already owe and how you have handled credit in the past, and estimates the loan it would be comfortable granting. You get an amount, an indicative interest rate, a term and an estimated monthly instalment. What you do not get is a binding commitment: the lender has not yet verified a single document, and it has not seen the car.
That distinction matters, because the two things it does not cover are exactly the two things that most often derail a deal. Verification can change the picture if your bank statements tell a different story to your application — undeclared debit orders, a garnishee, income that turns out to be commission rather than salary. And the vehicle itself has to pass muster: most South African credit providers will not finance a car that will be much older than ten years by the time the agreement ends, and high-mileage or grey-import vehicles are frequently refused outright, no matter how strong the applicant is.
Used properly, though, pre-approval is the single most useful hour you will spend on the whole purchase. It converts a vague sense of what you can afford into a rand figure, it surfaces problems on your credit record while you still have time to fix them, and it hands you the one advantage buyers almost never have on a showroom floor: the ability to say no and mean it.
The best time to apply is before you start test driving, not after you have found the car. Once you are emotionally committed to a specific vehicle, every number becomes negotiable in the wrong direction — a slightly longer term here, a balloon payment there — and the instalment quietly grows to fit the car instead of the car being chosen to fit the instalment.