Hay made some shakedown runs in Russell Christoffersen's RC Motorsport twin turbo Chev rear-engine dragster last month and accelerated into the low 6-secs range during Saturday's Test and Tune day at Meremere before uncorking a 5.993secs/242.32mph (389.9km/h) effort.
Attempts to lower the record further on Sunday were frustrated by a faulty turbo sensor which caused the engine to overboost as the car left the startline. With that rectified the team made another run that appeared to be an improvement but the timing system malfunctioned.
Hay was determined to run deeper into the "fives" and track officials left the timing gear and safety crew in place for a late final run.
"I didn't want to leave the track till we'd gone even quicker. I was determined not to be a one-hit wonder," she said.
The last pass, late on Sunday afternoon, tripped the timing beams at 5.991secs and slightly slower through the finish line speed trap at 239.70mph.
"Russell gave me a great opportunity and I'm so happy to achieve our goal and repay the faith he had in me. It's a big thing to put someone else in your car," Hay said.
"It's a cool car to drive. When you watch the dragsters you think they run nice and straight but you really have to drive it to keep it in the groove.
"There were a few different things to get used to. The parachute button was on the other side and the transbrake was also on the opposite side to our car.
"I think I was lucky to get the opportunity to drive a turbo rail because I have so much experience in our turbo car."
With her five-second goal achieved in only two weekends driving the dragster, the Pukehina mortgage adviser hasn't made any future quarter-mile calculations.
"I don't immediately have any big new goals but you never know what other opportunities might come along," she said. "We'll have Evil II out racing again in January with some small changes and we'll be trying to improve our national class records."
Hay holds national records in three drag racing classes with Evil II in both supercharged and turbocharged specification and she still holds a national CC/Altered mark in her former '32 Roadster that nobody has bettered since 2007.
