Cox was racing a re-built Mitsubishi Evo 8 during the event, which Cox Motorsport bought especially for the Race to the Sky.
He said they had a few mechanical problems but his team did really well to fix up the car in time for the main runs.
Cox said considering it was their first year at the event and they were racing a new car he was happy to finish fourth overall.
The rally driver said he would definitely be returning next year to have another crack and try to win the overall title.
Eight-time winner of the Race to the Sky, Japan's Nobuhiro "Monster" Tajima, had a bad crash during the event and had to pull out of the race.
He lost control on the notorious fourth corner of the course and plummeted down the hill. Fortunately he was not injured but his Toyota Super 86 was a mess.
Cox said the cliffs and high ridges were a bit daunting while racing up the mountain.
"There were some close moments getting a bit wide but you don't think about it," Cox said.
Perth-based McRae won the event in his Subaru WRC 98 in a time of 8min 17.6sec, while second place went to Australian Brett Hayward (8:24.6) who drove a RTTS Special. Ffitch (8:35.3) finished third.