Only two hundredths of a second separated Millen and second place getter Frenchman Romain Dumas.
The previous record holder Nobuhiro "Monster" Tajima failed to finish this year in his electric Suzuki after the motor burned out.
Dumas set a 9:46:18 time, and 10 race spots later Millen did it in 9:46:16. The Frenchman responded by publicly proclaiming he'd never race at Pikes Peak again and whingeing that it wasn't fair that all of the fastest drivers didn't run in order, and some enjoyed better weather in the morning - even though Millen was after him in the running order.
"I think he has said enough for me not to comment," said Millen, "I was a little shocked, but it must suck for Hyundai to beat Porsche two years in a row. His biggest frustration was waiting and the waiting caused us both to run in the rain.
"If the run order on the day was not class based and fastest to slowest, we both would have had a cleaner faster road - I agree with him on this."
Millen said setting the Genesis up for Pikes Peak wasn't as difficult as making a direct transition from drift car to hillclimb weapon.
"We had experience on brakes, threw the biggest stickiest tyres Hankook make on it, applied a road race rain set up from what I had learnt racing in a 'one make series' Hyundai Genesis in Korea last year. We did one day of testing local to the shop (RMR in Huntington Beach) witnessed a very fast lap time with a very comfortable balance and said 'this is strong enough for a class win'."
It was a bit more impressive than that, especially as Pikes Peak is very much the family event. Rhys' Kiwi motorsport legend father, Rod Millen, held the course record for 13 years in his purpose-built 900hp Toyota Celica, last seen at his annual Leadfoot Festival in the Coromandel.
"Dad was not present but had been all week - he was at Bonneville getting his rookie licence to be able to go over 200mph [320km/h].
"He called to congratulate me and said it was a better feeling than when he broke the record in 1994 and that he was very proud - such a champ."
This year's race - the 90th year it has run - was the first contested entirely on asphalt, leading to far more significant gains than the Rhys Millen Racing team had hoped for.
"This was a huge change - we expected to gain some 30 seconds for our class based on rear wheel drive on dirt over last year," he explained.
"This would give us an expected time of 10:20 to 10:30 and that was going to be fast in our minds. What was unexpected was that with a single setup for pavement we were running another two seconds a mile faster on the other sections because of a non-compromised set up, meaning slick tyres over rains, more aero and stiffer suspension settings.
"We were not the fastest overall this year during practice, so we planned on a class win. The amazing part is the unlimited cars I believe would have been in the 9:08 mark.
"The race played into our hands and when it became a race between Dumas and myself I drove harder than I ever have before. The fact the the course is fully paved reduces the need for high horsepower to push high downforce to get grip and a fast, efficient, balanced car is capable of posting very quick times."
To see Rhys Millen's record run, go to nzherald.co.nz/driven
