[1] In 2006, McKenzie made his debut in single–seaters, taking part in the Formula BMW UK series with the Promatecme – RPM team.

At the end of the year, he changed to the Fortec Motorsport team to contest the Formula BMW World Final in Valencia, where he finished 20th.

McKenzie continued with Fortec in Formula BMW UK for 2007, ending the season in eleventh position, with teammate Marcus Ericsson taking the title.

[4] In 2009, McKenzie made the step up to the British Formula 3 Championship with Fortec, racing in the National Class for older Dallara F307 chassis.

[8] McKenzie moved into the International Class for the 2010 season, staying with Fortec where he was joined by Oliver Webb and Max Snegirev.