The team placed fifth overall at Queenstown and by section had finished second in the entrapped section, fifth in controlled, technical and immediate, fourth in team leader, and third in medic and trauma team.
Rolleston finished first overall ahead of Feilding, Whitianga and Morrinsville respectively, he said.
Mr Fenwick, who is also operational support manager for the Greytown brigade, said the Rolleston team had deserved their win and outdid their performances in years past.
"Rolleston were also-rans over the past four years but their experience after the earthquakes and their coaching under some of the leading lights in the game really made a difference."
Mr Fenwick said four assessors are based in the Canterbury region and none in the lower North Island and that the Greytown team would be taking advice from assessors in the lead-up to their next competitive outing in Canberra next year.
He said the team will be self-funding the Trans-Tasman challenge and will be looking for sponsors.
Highlights for the team at Queenstown included the entrapped section, he said, during which "even the more fancied rescuers were put to the sword.
"The level of skill required to remove entrapped patients has risen dramatically over the last two years of competition and this event proved even the most seasoned teams were going to struggle to keep their place."
Mr Fenwick said each member is dedicated to their work and the challenges are not taken lightly.
"Road crashes affect everybody and if we can go out there and save only one life, it's worth it."