"I thought it would be a big help towards the budget to get the kids overseas," she said.
"It could pay for the tickets for service crew or whoever."
Mrs Cox couldn't believe it when she heard she'd won.
"I'm hoping the good luck travels with them when they're down in Dunedin [this weekend]," she said.
Tarryn, 22, said competing in the three-round Pacific Cup, part of the Asia Pacific Rally Championship, was the next goal for her and 20-year-old Sloan.
"We need to get that overseas experience. You learn so much driving on different roads and in different climates," she said. "It would be huge for our growth."
Initial hopes of competing in the cup this year were dashed when they failed to raise the approximate $90,000 required but with a fundraiser and plenty of door knocking planned Tarryn is optimistic of raising the cash in time for next year.
In the meantime, all eyes this weekend will be on Dunedin and what Tarryn describes as the fastest rally of the championship.
Since last month's Rally Wairarapa, where the pair had to settle for third after suffering two punctures, they have conducted two test days and are confident their Taslo Engineering Mitsubishi Evo 10 is in good shape for the fast southern roads. It's also the only one of the five Rally of New Zealand events to include night stages, which will test the strong bond between the two.
"It's a challenge," said Tarryn. "The trust between each other is really important. Sloan is relying on me even more, you have to up your game."
Unlike other siblings, Tarryn says there's no place for bickering between the two when they're on the road.
"We both have got the same goals in the car, there's too much at stake."
The 17-stage Rally Otago runs from tomorrow to Sunday on the gravel roads around Dunedin.
