Umbrărescu started his car racing career in 2016 by competing some races of the Renault Clio Cup for the Certainty Racing Team.[2]
In 2017 he joined the German RN Vision STS team to compete in the GT4 European Series Northern Cup with Gabriele Piana and Hendrik Still as his teammates.[3] He took four class victories and became vice-champion in the Pro-Am classification.
In 2018 he remained with the team to contest the GT4 European Series with Gabriele Piana as his teammate. He took his first overall win in the series at the Misano World Circuit. The pair of Piana and Umbrărescu finished the season as seventh in the Silver Cup. That year he also joined Leipert Motorsport to compete in a few selected races of the 24H GT Series and Lamborghini Super Trofeo Europe. At the 24 Hours of Portimão he took second place in the SPX class together with Gabriele Piana, John-Louis Jasper and Pavel Lefterov.[4]
In 2020 he joined Team Lazarus to compete in the International GT Open with Stefano Coletti. He only competed in the first two rounds without finishing a single race. He also joined Classic & Modern Racing to compete in the GT World Challenge Europe Endurance Cup with Pierre-Alexandre Jean and Seb Morris.[2] Ahead of the second round at the Nürburgring he was switched to from #108 car to the #107 car which he shared with Romano Ricci and Stephane Tribaudini.[6]
In 2022 he remained in the GT World Challenge Europe Sprint Cup with the same team. His teammate was Igor Waliłko.[9] The pair finished the season as tenth in the Silver Cup.
In 2023 he joined the Haupt Racing Team to compete in the ADAC GT Masters.[1] Together with his teammate Arjun Maini he took a second place in the opening round at the Hockenheimring.[10] Ahead of the second round it was announced that Maximilian Götz would be his teammate for the rest of season.[11]