The eight-episode series, which originally aired on Australia’s Fox Showcase and the UK’s Sky Atlantic, was co-written and co-directed by star Tim Minchin. He plays Lucky Flynn, a depressed musician driving to visit his dying mother, his treasured piano attached by trailer to his car. Distracted, he smashes into a Toyota truck driven by Meg (Milly Alcock), a feisty, foul-mouthed 16-year-old whose wrist is fractured in the crash. They strike up a grudging friendship and, with Lucky’s piano on the back of Meg’s truck, embark on a cross-country journey that detours into humorous and dramatic territory.

Minchin, 44, the provocative, multi-hyphenate Australian comedian, is best-known in the US as the composer/lyricist of Broadway’s “Matilda The Musical” and “Groundhog Day” and for his role as Atticus Fetch on Showtime’s “Californication.” He spoke to The Post from Sydney, where he lives with his wife and two young children, about Lucky and about working with Alcock.

Is this a story based on someone you know or on a personal interaction?

It’s a great set-up, but it’s not mine. The [series] creator, Chris Taylor, who’s known in Australia as a comedy satirist who doorstops politicians, had been trying to move into narrative television … and he sent me this one-page pitch, trying to make something that felt a bit like “Seinfeld” or “The Trip” with Steve Coogan. I thought the premise was great … and I recognized in myself the desire to make a drama. I wasn’t in the mood for comedy and didn’t want my next project to be flippant. I wanted to make something special.

Why weren’t you in the mood for comedy?

I’d moved to LA and given up my touring career for a huge project I worked on for years, an animated feature [“Larrikins”] at DreamWorks. I’d be acting, composing, directing. Then Universal bought DreamWorks and trashed four years of my life. I’d turned 40 and then “Groundhog Day” closed early on Broadway. I was a bit battered. We’d been living away from Australia for 12 years … and I guess I was really thinking a lot about going home and about spending so much time away from my family. So the story of a guy carrying a burden across the desert to his home, where he hasn’t been for eight years…I felt I brought a bit of emotional complexity to the role.

Tell me about Milly Alcock, who’s terrific as Meg.

She’s an absolute scene-stealer. An actress friend of mine, Kate Mulvany, who plays the nun in “Hunters” [on Amazon] and is also a writer on “Upright,” had worked with Milly in a small role in an Australian drama … and brought her up. We auditioned loads of people and were looking for a diamond-in-the-rough, someone bolshy and intuitive. We wanted someone maybe a bit plainer and rough-around-the-edges, but her talent was undeniable. She’s incredibly independent. She was 18 when we were shooting “Upright” and she didn’t bring a friend or a chaperone or her mum or anyone to the shoot. Every now and then we’d talk her into coming out for a beer after work, but she usually went back to her room and read books or worked on learning the script. She had a boyfriend in Sydney who never came to visit. They stayed in contact online. Early on the director, Matt Saville, and I had a chat and we decided we shouldn’t get too much up in her grill or direct her too much. Her instincts were so strong.

Did you two bond offscreen like your onscreen characters?

I certainly didn’t need her to be my friend, this 40something bloke who’s going to hang out with her. But over time we got really close. We shot chronologically, so those early scenes we didn’t know each other at all.

Will see a second season of “Upright”?

It’s possible. It really does wrap up in Episode 8 … but we have a Season 2 mapped out.