The 16-foot snake crawled into the engine of Marlene Swart and Leon Swanepoel's Renault Megané from the grass underneath.
The bonnet was left open after the pair broke down near Kruger National Park, where they had visited to see lions.
After about an hour, the reptile was eventually enticed out of the vehicle.
Marlene Swart is quoted by The Mirror as saying: "It was certainly a once-in-a-lifetime experience. I was totally in shock and terrified.
She added: "It eventually sailed away unharmed. Later that evening we had a good chuckle about the reactions of the bystanders when it exited the vehicle."