Father Arthur Dontje supported his sons Indy and Milan with their own karting team early in their careers.

Racing in the ADAC Formel Masters Dontje joined Team Motopark, part of the Lotus F1 junior program.

Dontje challenged Nabil Jeffri for third but had to settle for fourth place, scoring the fastest racelap in the progress.

[13] With Rowe Racing switching to BMW, Dontje remained in the AMG Customer Sports program with HTP Motorsport for 2016.

Dontje ran the full 2016 Blancpain GT Series Endurance Cup with teammates Luciano Bacheta and Clemens Schmid.

With the Mercedes-AMG GT Dontje scored two podium finishes, at Zandvoort and the Sachsenring, to place thirteenth in the series championship.