Jos Verstappen has said that his son Max is training harder than ever for 2017.
Young Verstappen, 19, is touted as a potential title contender for 2017, when the cars will be much more physically demanding to drive.
His father Jos, a former F1 driver, says that is why Max has been quiet in the last few weeks.
"Max is completely exhausted every evening, sitting on the sofa. It's good," he told Dutch broadcaster Ziggo Sport Totaal. "Then he does not talk so much!
"No, Max is quiet, but I also feel his enthusiasm. Because as far as I know, the expectations at Red Bull Racing are quite high."
Jos said that although his son is continuing to develop and improve in F1, he is happy to watch from the background, electing not to attend every grand prix.
"My big goal was always to bring Max to Formula 1," Jos said. "That's done. In the meantime, he has established himself as a top driver. My presence is simply not necessary."
Indeed, Max is now almost completely independent, living alone in Monaco.
"Sure, I miss Max," said Jos. "I recently talked to my daughter about it, that it's a bit strange that Max is not here. But he now has his own life in Monte Carlo and is extremely busy.
"I'm not worried about Max. I know he is in very good hands with Red Bull. Everything is superbly organised. He certainly does not need me.
"The change is also positive for me - I am more relaxed than before. Clearly I carefully watch what is going on, but not more."
The first grand prix of 2017 will be the Australian Grand Prix on March 26.
