The former world masters champion (Dorma) drove hard from the beginning of the undulating 79km course, which started at the Knysna Elephant Park, to cruise into the finish at Thesen Harbour Town in 3:22:03.
Hanco Kachelhoffer and Colin Noel (Altech Autopage) won the team event in 3:29:03.
In the women’s race, Robyn de Groot (Ascendis Health) repeated the form that brought her a third consecutive national marathon title last week to claim the stage in 3:45:43.
Pfitzenmaier, who took overall victory in the team category alongside Renay Groustra last year, said the revised first stage had been much tougher than the previous year.
“It was a beautiful route but technical, muddy and rough; the trails were quite challenging,” he said.
The 44-year-old said he had felt good as he negotiated the technical descents after the first big climbs.
He was first through waterpoint one at Packwood Wine Estate after 22km and maintained his lead through the Petrus se Brand section of the Garden Route National Park.
He was well and truly in charge of the stage by the time he had reached the second waterpoint on the Uniondale road after 43km.
The final stretch, which included race organiser Patrick Mostert’s eight kilometres of “secret” single-track through indigenous forest en route to Simola and the finish, was a mere formality.
Second-placed solo rider Dylan Rebello (Jeep) lost valuable time when he suffered a sidewall cut in the first 5km.
“Eventually I got it plugged and just went full gas,” said Rebello.
“But I think I went too hard at the start trying to catch up, so towards the end I had to dig really deep.”
The 20-year-old local said the race was far from over.
“This is my home territory and day two passes right behind my house, so I hope to make up the time over the next two days.”
George-based Kachelhoffer and Noel kept a consistent pace throughout the stage to take a comfortable lead into day two.
“Keeping up with Nico wouldn’t have been wise because you run the risk of a mechanical because he goes so fast on the downhills,” said Kachelhoffer.
“There were also quite a few steep climbs towards the end and Colin started cramping a bit, so we just had to manage our speed.
“It was a good start for our team.”
Husband-and-wife duo Andrea and Steven Shirley (Merrell) were first on the day to claim honours in the mixed race in 4:08:38.
Nicola Giliomee and Marleen Lourens took another category win for Merrell when they finished first in the women’s section in 4:11:36.