McCrostie was runner-up when the 1.2km gravel climb was first staged last year.
On Saturday, he set the fastest time on every run, recording times in the 54sec bracket on his first two runs then identical times of 52.91sec on the final two.
Eastern Southland Car Club spokesman Roger Laird said the fact McCrostie was able to compete in his Mitsubishi Evo was a tribute to the hard work of McCrostie and his crew, Paul Goatley, Murray Marshall and Dean McCrostie.
"Just days out from the event, it appeared the reigning Southern Twin Peaks Challenge Champion would have to revert to his older, two-wheel-drive Nissan Bluebird Turbo as the Evo was far from ready for the event. However, two very late nights on Wednesday and Thursday had the car on the start line," Laird said.
Last year's third placegetter, Glenn Frew, of Outram, finished second in his Evo.
Last year's champion, Gore driver Andrew Graves, was third in another.
Craig Abernethy, of Gore, was fourth in the Mitsubishi Evo 4 now owned by Paul Cross. Abernethy recorded 54.34sec, while Cross, who shared driving with Abernethy, had a best of 54.97sec to claim fifth.
Abernethy won class D for 4WD cars from Cross and Krammer, while Hey took class C for cars of 1601cc and over from Paul Goatley, of Balclutha, and Chris Lange, of Invercargill.
Class B was won by Hadley MacKay, of Arrowtown, who beat last year's class winner, Dean Bond, of Balclutha, and Phil Terry, of Wrights Bush.
David Scoles, of Lumsden, shone in his Toyota Starlet to win the small car class from Alan MacDonald, of Gore, with Alan's son, Caleb, third in the Suzuki Swift they shared.
Robert Scott, son of the late Bob Scott, won the sports and racing car class in a V8-powered midget. He also drove his father's Scott Special.
Graeme Taylor, of Temuka, and Bob Dunstan were second and third respectively in the class.
Gus Osborne, of Gore, proved a crowd-pleaser in his V8 Falcon, while Jay Kluttz, of Gore, rolled his Holden Barina GTi on the third run - fortunately without being injured.
The hillclimb, a joint promotion between the Kaitangata Promotions Group and the Eastern Southland Car Club, is the first round of the Southern Twin Peaks Challenge.
