Mikkelsen was crowned champion of the WRC’s premier support category at Rally RACC - Rally de España last weekend despite not starting the rally.
He had planned to end his season at FORUM8 ACI Rally Monza (18 - 21 November), but headed for the Salou service park after main title rival Mads Østberg suffered a costly puncture on Friday.
The title was decided when neither Østberg nor Teemu Suninen scored enough points to catch him.
"My plan was to go to Spain to have some meetings and then drive back to Monaco on the Saturday," explained Mikkelsen, "but when Østberg had his problems on day one, the chances were really high to be crowned champions already.
"It was super weird to sit there in normal clothes and from one second to another you suddenly become champion."
The Norwegian chalked up three wins in Monte-Carlo, Estonia and Greece, but also suffered setbacks after off-road excursions in Croatia and Italy.
He admitted being surprised at the level of competition and explained how the pace has stepped up over recent years.
"My goal for the season was to try to dominate as much as possible,” he said. “But I have to say, the level was higher than I anticipated.
"I remember doing some WRC2 rounds in 2017 with the Škoda and we were winning super easy, so I expected it to be a little bit like the same. But there were a lot of past WRC drivers and I was surprised that the level has been rising a lot since 2017.
"So, yeah, it didn't come easy at all. I really had to fight and drive very fast, so it was a nice year,” he added.
Mikkelsen hopes to wrap-up the European championship title this weekend in Hungary. He will still contest Monza to help Toksport try to secure the WRC2 Teams’ title.