Our C43 does the same I don’t think you can change it. It’s probably better for the engine and tranny to warm up in comfort mode. Sport and sport + are much more aggressive shifts. It’s the same as the ECO it always turns itself ON. My ML stays in sport.I can't figure out how to set the driving mode in SPORT and keep it in SPORT. It defaults every time to COMFORT at startup. Can anyone assist? Thank you in advance!