Despite driving year-old cars, Carroll was always an outright front runner and he dominated the class winning the title with a record points tally.

In 2003, Carroll moved up to Championship Class British Formula 3, but due to lack of finance, he had little stability and finished the year having driven with three different teams (8 podiums in a row with Menu), before competing in part of the Formula Three Euroseries season, where despite being new to both team, series, track and tyres, he finished in the points in his first race.

He also partnered and outperformed future Formula One driver Nico Rosberg in an end of season event in South Korea.

He continued in Formula Three throughout 2004, finishing as runner up to Nelson Piquet Jr. before joining the 2005 GP2 Series, replacing Hayanari Shimoda at the Super Nova Racing team just before the start of the season.

It soon became clear that due to Carroll's continued lack of sponsorship, the Racing Engineering deal saved him from having to drop out of top line motorsport altogether.

This coupled with a driver error while leading race two in Hungary cost Carroll a lot of points that, should he have gained them, he would have been in contention for at least third in the championship.

For the start of the 2007 season, Carroll was driving a two-year-old Audi A4 in the German DTM series for the Futurecom TME team.

[7] Carroll also went on to claim victory in the first race at the Hungaroring, despite starting sixth and changing all four tires during his mandatory pit stop.

A1 Team Ireland became the fourth A1 Grand Prix champions, after a title battle which went down to the final round in Great Britain.

[14] IndyCar Series team Andretti Autosport announced that Carroll was to take part in some races during the second half of the 2010 season.

On 2 July, Carroll made a one-off appearance in the Formula Renault 3.5 Series at the sixth round of the championship where he finished fourth and third in the two races.