[2] He holds a Doctor of Engineering from the University of Michigan and has worked for Freightliner Trucks, Daimler AG and Tesla, Inc. Guillen previously studied in France at ENSTA Paris.

Beginning in 2003 Guillen worked at Freightliner Trucks, reporting to the company CEO Rainer Schmueckle.

[8] Guillen was project leader for the Freightliner Cascadia program, which was plagued with repeated recalls of hundreds of thousands of vehicles for dozens of reasons including multiple brake system design failures, and wiring systems designed and installed backwards.

[12][15] Whilst demonstrating the Tesla Model X at the North American International Auto Show in January 2013, Guillen stated that he did not regret the move to Tesla in California, but did miss the German dishes of Käsespätzle and Maultaschen, plus visiting the Stuttgart Ballet.

[6] During ramp up of the Tesla Model 3 in June 2018, Elon Musk stated who should be contacted to offer help, with Guillen listed as overseeing General Assembly 4 (GA4):[18] Wherever you are in the company, if you feel you can help out in any of those areas, please check in with Jat Dhillon on GA3, Jérôme Guillen on GA4 and Omead on EoL and JB Straubel or Chris Lister on Module Zone 4.Guillen left Tesla in the role of president, Tesla Heavy Trucking on 3 June 2021.