Robert Downey Jr.'s Son, 11, Pokes Fun at Dad's Car Skills in Trailer for 'Downey's Dream Cars': Watch

Robert Downey Jr.'s son Exton, 11, made a surprise appearance in the trailer for the actor's new reality TV series

Robert Downey Jr.'s new reality TV series has a surprise guest star — his son, Exton!

On Wednesday, HBO Max dropped the first trailer for the Iron Man actor's new reality TV series, Downey's Dream Cars. The show will follow the star as he aims to restore six of his classic cars. The trailer, which Downey Jr. reposted to his Instagram Story, featured a guest appearance by his 11-year-old son.

While the pair are eating lunch together, Downey Jr. starts using the food around them to demonstrate the work he's doing on his cars. He tells Exton, "This is a clue you'll never guess," to which his son quickly answers, "It's a biodiesel conversion," beating his dad to the punch.

As the actor brags about being a "gearhead" and a "grease monkey," his son turns to the camera and quips, "Are we sure he's the right guy to be hosting this show?"

Never miss a story — sign up for PEOPLE's free daily newsletter to stay up-to-date on the best of what PEOPLE has to offer, from juicy celebrity news to compelling human interest stories.

Related:Robert Downey Jr. Turns 58 as He Shares Video Celebrating His 'Blessings' and 'Sweet' Marriage

Downey Jr. shares son Exton and daughter Avri, 8, with his wife Susan Downey. He also shares son Indio, 23, with ex-wife Deborah Falconer.

The Avengers star is notoriously private about his kids but shared a sweet video featuring his children in April in celebration of his 58th birthday. He took to Instagram to post a montage that looked back on his 57th year, which began by ringing in his 58th birthday with wife Susan and his three kids.

"57, you've been too kind. With gratitude, I shall rewind," he captioned the beginning of the video. Among his favorite moments from the year was a time when he let Avri and Exton shave his head ahead of filming a project.

"Sorry to interrupt but I need your help," Downey Jr. began the video as he entered a room where his kids were carving pumpkins. "You know how I'm starting this project soon?"

"Yeah, The Sympathizer?" said Avri, as Exton added, "Yeah, you're playing like five roles or something."

"Right. Well anyway, I don't want to wear a bald cap, so will you guys shave my head?" he asked his children, who look up in confusion.

"Is that even appropriate?" Avri asked with a smirk before she and her brother start shaving their dad's head.

For more People news, make sure to sign up for our newsletter!

Read the original article on People.