He dominated the championship so much that an obligatory pit stop for tire change was introduced at the end of the season in an attempt to level the advantage, but Arden managed to do better pit-stops overall than other teams and still came out on top.

Wirdheim became the first Swede to win the championship in its 19-year history, breaking Justin Wilson's previous record of most points won in one season of the series.

However, at Monaco, when driving to an easy win on the streets of Monte Carlo, Wirdheim slowed down to wave at his pit-crew believing he already had taken the chequered flag and was overtaken by Nicolas Kiesa, metres away from the actual finish line.

After turning down an offer to drive Champ Car, Wirdheim signed with Jaguar as third driver performing the Friday testing for the team at Formula One Grand Prix weekends during the 2004 season.

While taking up a new challenge in 2018 as a Formula 1 TV-commentator for Viasat, Wirdheim has made guest appearances in Porsche Carrera Cup Scandinavia.