 Also during 2005, Martínez contested some rounds of the A1 Grand Prix Series.In 2006 Martínez returned to Atlantics with the US RaceTronics Team, and repeated his fifth place in the championship despite a challenging season in which he switched teams halfway through the year, but still managed to continue his success on Mexican soil by finishing third at the Monterrey, Mexico event.In 2006, Martínez joined Forsythe Championship Racing in Mexico City to pilot the Lola-Ford-Cosworth in his Champ Car debut.