He said the car started making "rickety noises" before he stopped.
He left the car after he noticed smoke billowing from under the bonnet.
The man had bought the car for $1200 a few months ago, to use as "bit of a runaround", before he bought another vehicle.
It was not insured.
He was shocked but philosophical about the incident and was thankful his golf clubs in the boot, which cost him double what he paid for the car, were not damaged.
The man stayed overnight in Oamaru and planned to travel back to Dunedin by bus today.
Weston Volunteer Fire Brigade Station Officer Geoff Parsons described the fire as "stubborn", as most vehicle fires were, because of the combination of fuel, oil and alloys.
"This one was just another car fire. It could have been a lot worse if it was a lot more windy and headed to the paddock next door."
One lane of the highway was closed while the fire was extinguished and traffic was managed by police.