Adam started out in 1993 competing in karting events, which he would continue to do so until 1999. After a year without doing anything notable he returned, winning the 2000 British Formula Ford Winter Series. He moved on to the British Formula Ford competition in 2001, before successfully making the move to British Formula Three B-Class in 2002 with the Sweeney team. Despite driving year-old cars, Adam was always an outright front runner and he dominated the class winning the title with a record points tally.
In 2003 Adam moved up to Championship Class British Formula Three, but due to lack of finance, he had little stability and finished the year having driven with three different teams, 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 Angelo Piquet before joining the 2005 GP2 Series, replacing Hayanari Shimoda at the Super Nova Racing team just before the start of the season.
Although Adam's pre-season preparation for GP2 left him at a disadvantage to all the other drivers due to the lateness of his race deal and consequent lack of testing with his new team, he was immediately competitive, briefly challenging for the championship before slipping back as the season progressed due to reliability setbacks and on-track incidents.
Despite continually having trouble raising a budget for his racing, he has still managed to outperform drivers who have had funding readily available to them, including 2005 team-mate, and ex F1 driver, Giorgio Pantano. His undoubted talent caught the eye of Formula One and in 2005 he was signed as a test driver for Formula One team BAR-Honda. For the 2006 GP2 season he surprised many in choosing to join the Racing Engineering team when his previous team had a better chance of picking up the title. It soon became clear that due to Adam's continued lack of sponsorship, the Racing Engineering deal saved him from having to drop out of top line motorsport altogether. He has since removed himself from the Honda driver program sensing a lack of opportunity as Button and Barrichello would be hard to replace.
The only real high point of the 2006 season was a pole position, third place and second place combo at his home track, Silverstone. It was clear throughout the season, however, that Adam's team was not as strong as the majority of the other teams in the series. This was highlighted many times due to car failures that cost him many points throughout the year. As well as this, the car was distinctly slower and he also had trouble with other drivers hitting him from behind. This coupled with a driver error while leading race two in Hungary cost Adam a lot of points that, should he have gained them, he would have been in contention for at least third in the championship. As it was though, Adam's 33 points was enough to give him eighth place (equal points with seventh-placed Gianmaria Bruni with Bruni ahead having scored more wins). Adam scored all of his team's points, outscoring his old team Super Nova Racing.
DTM, GP2 & A1GP
Adam driving for FMS International at the Monaco round of the 2008 GP2 Series season. For the start of the 2007 season, Adam was driving a two year old Audi A4 in the German DTM series for the Futurecom TME team. On 26 June it was announced that he would replace Antônio Pizzonia in the FMS GP2 team for the event supporting the French Grand Prix. Adam won at the Silverstone round of the GP2 series and scored 4 other points to take a total of 13 in one weekend, only his second back in GP2, in a car that had only scored one point beforehand. It was announced on 13 July that he has left the DTM due to sponsorship problems, and will concentrate on GP2 for the rest of 2007. Adam 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. The season didn't end so well for Adam, as he scored only 2 points in the last three races despite being in contention for much more. However, he did finish in seventh place, ahead of many drivers who, unlike Adam, had completed the entire season. During this time, Adam had tested the A1GP car for Ireland, impressing everyone at Silverstone and so for the second event onwards, Adam signed up to race in A1GP. His first weekend demonstrated yet again what a talent he was as he got Ireland's biggest points haul in the history of A1GP by netting a podium in his first race and despite starting 18th on the grid due to being blocked in qualifying, 6th in the feature race. Later in the season, he won the Mexico City feature race, Ireland's first win in A1GP. He also finished on the podium at Brands Hatch, en route to helping Team Ireland finish 6th overall in the championship.
Adam began the 2008 GP2 Series season without a drive, but when Adrián Vallés was dropped by FMS International after the first round of the season, he took part in four races for his old team. He was then replaced by Marko Asmer.
For 2008/2009, Adam returned to A1GP and Team Ireland again. As of the Portuguese event, Adam leads the drivers championship by two points from Switzerland's Neel Jani.
Adam announced in April 2009 that he has been approached by two F1 teams in negotiation for a driver's seat for 2010.