2020

Having started kart racing at the age of seven,^[2][3] Dufek followed up his karting career with a move into single-seaters in 2020, competing in the F4 Spanish Championship with MP Motorsport.^[4][5] His season would start out slowly compared to his teammates Kas Haverkort and Mari Boya,^[6] with just one podium and pole position scored in race three in Navarra to show for his efforts.^[7] Dufek's results would improve afterwards, getting two back-to-back third places in the third round at Jerez, and followed that up by finishing second twice at the following event in Valencia, crossing the finish line less than a second after teammate Haverkort.^[8] The Swiss driver scored three more podiums in the latter half of the campaign, finishing the season in fourth position in the standings, tied on points with fellow rookie Thomas ten Brinke.^[9]

2021

In 2021 Dufek moved to Van Amersfoort Racing, partnering Oliver Bearman and Nikita Bedrin in the Italian and ADAC Formula 4 series.^[10] His campaign in the former championship began in similar fashion to his 2020 season, having to wait for a podium until the eighth race of the season at Vallelunga.^[11] He scored another podium in Imola, and went on to make a bold call to switch to rain tyres during the final race at the Red Bull Ring, which allowed him to charge to second place. His weekend of the season would come in Mugello: after having taken all three pole-positions of the event in qualifying,^[12][13] Dufek finished second in the first race and came out victorious in race 2, having lost the lead at the start but taking it back after overtakes on Oliver Bearman and Sebastián Montoya.^[14][15] The Swiss ended his season in the Italian championship in seventh place after amassing 154 points.^[16]

In the German championship Dufek would get his first podium in a VAR podium lockout in race 2 at Zandvoort, finishing second.^[17] Dufek then went on to have two further races in which he narrowly missed out on taking victory, losing out in back-to-back races at the Hockenheimring and Nürburgring to Luke Browning and Tim Tramnitz respectively.^[18][19] His ADAC F4 season also ended with him sat in seventh, having skipped the fourth round at the Sachsenring.^[20]

2022

Having taken part in post-season testing with MP Motorsport and Van Amersfoort Racing at the end of 2021, Dufek signed for the latter team to compete in the Formula Regional European Championship, driving alongside Levente Révész and Kas Haverkort.^[21][22] Before the season, the Swiss driver competed in the first three rounds of the Formula Regional Asian series for Hitech Grand Prix, amassing two rookie podiums, ending ^[23][24][25] The start to his campaign in the European championship would prove trickier, as Dufek scored just two points in the first ten races, far from teammate Haverkort. However, a sudden upturn in form at the Hungaroring round with strong points finishes, followed by a double podium at the Red Bull Ring after the summer break, propelled the Swiss driver into the top 10 in the standings and rookie title contention.^[26][27] Dufek arrived at the season finale at Mugello tenth in the standings, 11 points off rookie leader Leonardo Fornaroli. He put pressure on the Italian with a podium in race one and a front row start in race two,^[28] but a late mistake fighting with Hadrien David saw him drop three positions and eventually miss out on the rookie championship by 4 points. This was, however, enough of a points haul for Dufek to leapfrog MP Motorsport's Mari Boya and secure ninth place in the final overall standings.^[29]

2023

At the start of 2023, Dufek raced in the 2023 Formula Regional Middle East Championship with PHM Racing.^[30] He would go on to take his first Formula Regional victory at Kuwait Motor Town, only to have it stripped away due to a technical irregularity.^[31][32] He finished the season sixth in the standings with two podiums to his name.

Dufek remained with Van Amersfoort Racing for the 2023 Formula Regional European Championship.^[33][34] Despite a maiden pole position at the Hungaroring,^[35][36] Dufek experienced a drop in speed due to what he described as a "recalcitrant engine", and opted to pull out of his contract during the summer break. He sat 9th in the standings at the time.^[37]

2023

Dufek was called up by Campos Racing for the final round of the 2023 FIA Formula 3 Championship at Monza, replacing Hugh Barter.^[39][40] After spinning out of qualifying, he finished 14th in both races, enough to propel him to 29th in the standings, ahead of six other drivers.^[41][42] He then tested for PHM Racing during the post-season test.^[43]

2024

For 2024, Dufek stepped up to FIA Formula 3 full-time, joining PHM AIX Racing for his first full Formula 3 season.^[44]