Jefferies began his motor racing career at the age of six years in karting, where he was active until 2008. 2009 joined Jefferies at the age of 14 years into formula racing and competed in the Formula BMW Pacific for Eurasia Motorsport. He won two races and finished third in the championship. In 2010 he started the season in the Formula BMW Pacific for Motaworld Racing, but lost his cockpit after the second race weekend. Jefferies had budget problems at this time.
2012 Jefferies received a cockpit in Formula 2 Though he initially stood on the starting list, he did not report for the first race weekend. He rose only to the third event in the series one. He scored regularly points and was twelfth in the championship. 2013 Jefferies was without a fixed cockpit. He took part in two races of the North American Indy Lights. He started for JMM / BHA with Curb Agajanian -. A fifth place was his best result.
- 2001-2008: Karting
- 2009: Formula BMW Pacific ( 3rd place)
- 2010: Formula BMW Pacific ( 15th place)
- 2012: Formula 2 ( 12th place)
- 2013: Indy Lights (11th )
- 2014: GP2 Series