Dillmann began his career in motor racing in 1992 at the age of three years in karting, which he held until 2002. 2004 moved Dillmann into formula racing and launched in various Formula Renault championships. The most successful was he in the Belgian Formula Renault 1.6, in which he finished fifth overall with a win. 2005 Dillmann took part in some races part in the French Formula Renault and Formula Renault 2.0 Eurocup, but scored no points. 2006 remained Dillmann in both series and improved in the French Formula Renault on the tenth and in the Formula Renault 2.0 Eurocup to eighth place overall.
2007 moved Dillmann in the Formula 3 Euro Series for top team ASM Formule 3 With a second place as best result, he finished the season in ninth place overall. In winter 07/ 08 season he played two rookie training in the A1GP series, but for the team of Switzerland and not the French. 2008 Dillmann initially remained in the Euro Series and went for SG Formula at the start, but left the team after three race weekends, after Red Bull had withdrawn as its main sponsor. In the rest of the season Dillmann returned for the A - driver team Jo Zeller Racing starting for a race weekend back and scored a third place. He also competed at the last three races of the Italian Formula 3 Championship, where he eventually finished seventh overall. Also in 2009 found Dillmann no cockpit for an entire season, and that started with eight races in the 2009 Formula 3 Euro Series season. Successful ran it for Dillmann in the German Formula 3 Cup, in which he three of six races in where he had gone to the start, and won at the end of the season finished sixth overall. 2010 remained Dillmann in the German Formula 3 Cup. With a total of six victories, he won the league title before Daniel Dept. He also took part in a race weekend of the Italian Formula 3 part and finished the race in second place.
2011 Dillmann went first for Carlin in GP3 Series at the start. Already after the first race weekend in which Dillmann scored a third place, he was replaced by Daniel Morad. For the third race weekend, he returned for the Addax team starting in the GP3 series is back and broke Dominic Storey from. He finished the season in 14th place overall. In addition, Dillmann took in 2011 to some Formula 3 race. Twice he took as a guest part in a Formula 3 Euro Series weekend, scoring a third place as best result. In addition, he stepped up to the Grand Prix de Pau and a race weekend of the German Formula 3. At the end of the year he took part for iSport International at the GP2 Final in 2011 and finished it in sixth place. 2012 started Dillmann for Rapax in the GP2 series. In the third race weekend in as- Sachir he won the sprint race. It was his first GP2 victory. After the fifth race weekend he lost his cockpit due to budget problems. For a race weekend, he took over the car his team Kollegens Ricardo Teixeira, for another race weekend, he returned to his original vehicle. Dillmann was on points best pilot in his team, finishing in 15th place overall. Dillmann said after his cockpit loss that unfortunately pilots would go without talent but with budget in the GP2 series.
2013 Dillmann received a GP2 cockpit at Moto Park Academy, which supervised the newly created project Russian Time. In the main race at Silverstone and Monza he finished third. At the last event at the Yas Marina Circuit Dillmann moved in a collision to a neck injury, so he no longer came into use in the last race of the season. Dillmann finished the season with 92 points in tenth place overall from and subject so that internally Sam Bird, who with 181 points for second place. The two together won the team title with Russian Time of the GP2 series. For the 2014 GP2 Series season Dillmann had a contract with Moto Park Academy. However, since this team lost the support of the Russian Time project, this commitment did not materialize.
- 2006: French Formula Renault ( 10th place )
- 2007: Formula 3 Euro Series (No. 9)
- 2008: Italian Formula 3 ( 7th place)
- 2008: Formula 3 Euro Series (No. 18)
- 2009: German Formula 3 ( 6th place)
- 2009: Formula 3 Euro Series (No. 30)
- 2010: German Formula 3 (Master)
- 2010: Italian Formula 3 ( 13th place)
- 2011: GP3 Series ( No. 14 )
- 2011: German Formula 3
- 2012: GP2 Series (No. 15)
- 2013: GP2 Series (No. 10)