Hired by Brun Technics on graduation, he worked on both the EuroBrun F1 team and the 1990 design of the Judd-powered Brun C91 sports car. In 1991 he was hired as aerodynamicist on the Allard J2X-C sports car, and subsequently worked on Indycar development for Newman-Haas, Lola Cars and Swift Engineering.[3]
In 1995 he moved to Formula1 with Jordan Grand Prix as an aerodynamicist,[3] becoming chief aerodynamicist in 1998. In 2002 he followed Mike Gascoyne to Renault F1, and then joined Ferrari in 2004 as chief aerodynamicist.
He joined McLaren Racing in 2010,[3] but was placed on gardening leave in late 2011, ahead of his joining with Gascoyne again at Caterham F1 as performance director in 2012.[3][4]
Following his career in F1, Iley is the Director of Iley Design.[5]