He was a regular competitor in Champion of Oulton Park Formula Ford series from 1985 through 1997, and had top three championship finishes between 1995 and 1997.

In 2003, he made his debut in the 24 Hours of Le Mans, racing a Saleen S7-R for Graham Nash Motorsport alongside Thomas Erdos and Pedro Chaves, the car being sponsored by some of Newton's companies.

In 2010, Newton, Erdos and Wallace finished third in the LMP2 Class at Le Mans in a Lola HPD Coupe, and Newton and Erdos won the Le Mans Series LMP2 Drivers Title, with RML winning the LMP2 Team title, accompanied at different races by both Andy Wallace and Ben Collins.

For 2012, Newton stepped back from the troubled ELMS series due to a lack of funding from ailing business interests, and undertook the development of a Speed Euroseries CN car, bringing the Tiga Race Cars name back to Sportscar racing with the Tiga CN012, leading the development activities, and also as a driver, partnered by Dean Stirling.

Newton completed four rounds in the 2018 Master Endurance Legends, Imola, Silverstone, Nurburgring and Spa achieving 8 Class pole positions, 8 fastest laps, and 8 wins for LMP2 cars from 2000 to 2005.

Newton still competes in the Masters Endurance Legends regularly with the EX257, having taken 4 class wins out of 6 races after the Silverstone Classic.