A bit of strategy also helped Cox's win. Each race included a short-cut "joker lap" which drivers could use just once in each race.
"I decided to take the joker at the first chance. That way I knew where everyone was and whether I needed to push any harder."
Cox was driving the spaceframe Mitsubishi Evo originally built by Aucklander Andrew Hawkeswood for an attack on the Pikes Peak Hillclimb in the USA.
"The car probably has too much power for such a tight course. We tuned it for the Leadfoot Hillclimb and it had 550kW at the wheels. It would be better here with more low down torque."
In the final Cox built up a handy lead and came home ahead of Australian Marcus Walkem (Lancer Evo 9) with Tauranga's Phil Campbell (Lancer Evo 9) taking third.
A strong drive from Tasmanian Steve Glenney clinched the 4WD Rally Car final, backing up a win in Australia's major rallycross event in 2015.
Glenney started on the second row of the grid but quickly worked to second place and then hit the front with an early dive to the joker lap.
"It was good to come over and compete against the Kiwis - there are some really good drivers here," said Glenney.
"It's a great event and I enjoyed the racing. Hopefully the event can be built up for the future."