The announcement was made in the wake of last weekend’s Le Mans 24 Hours, which ended in disappointment for Dillmann as the Vanwall Vandervell Le Mans Hypercar’s Gibson engine suffered a terminal failure in the morning hours.
Dillmann was sharing the car with Esteban Guerrieri and Tristan Vautier, a last-minute replacement for 1997 Formula 1 champion Jacques Villeneuve, but the new car proved off the pace of its Hypercar competitors on its debut at La Sarthe.
The engine failure meant Dillmann has failed to finish in any of his four Le Mans starts for the Austrian-entered team.
“It’s important to say I have left Vanwall on good terms,” Dillmann told Autosport. “I have done a lot of races for the team and I just felt it was time to try something else.
“Of course, it’s a risk [to leave], because I don’t have anything else right now, but I felt I had to do this to try and get a seat elsewhere. I think I have it in me to do a good job for a team that is fighting at the front, and I want to push to be in this position.
“I’m not aiming to be a big star, but I think I can be a good asset to a team. I think I have proved how reliable I am in all conditions, and that I am a driver who can be counted on.”
Dillmann was keen to pay tribute to the Vanwall team and its founder Colin Kolles despite their lack of success together.
“I will never speak badly about the team,” he added. “I have a lot of respect for the effort they are making. Colin gave me the chance to do my first Le Mans [in 2018], which is not nothing, and we did a lot of races together. I wish them the best.
“It’s just I felt I owed it to myself to go out of my comfort zone and try to get an opportunity where I can fight for better results in the short term.”
Dillmann first raced for ByKolles in the previous-generation CLM P1/01 LMP1 car for the 2018-19 WEC superseason that encompassed two editions of Le Mans, and made his third start at La Sarthe in 2020 in a one-off entry that marked the old car’s farewell.
The 34-year-old has also raced in categories such as the now-defunct Formula Renault 3.5 series, which he won in 2016, Super Formula, and Formula E.
Vanwall subsequently announced that the place in its line-up for the next round of the WEC next month at Monza will be taken by SUPER GT veteran Joao Paulo de Oliveira.
Brazilian de Oliveira, who is currently racing for the Kondo Nissan GT300 squad in the Japanese championship, previously spoke of his desire to race the Vanwall LMH after testing it at Barcelona last year, only to lose out on a seat in the squad to Villeneuve.