Cas & Dylan, starring Jaws actor Richard Dreyfuss and Orphan Black actress Tatiana Maslany, is showing at the Glasgow Film Festival this evening.
The movie tells the story of terminally ill doctor Cas Pepper (Dreyfuss) who finds himself on the run driving west across Canada with a 22-year-old writer Dylan, played by Maslany.
Priestley shot to fame in the 90s playing Brandon Walsh in the TV series Beverley Hills 90210 and has since combined acting with directing.
He has directed several episodes of the HBO Canada series Call Me Fitz in which he stars, and has directed other TV series, TV movies and feature documentary Barenaked in America.
Priestley, from Vancouver in Canada, had long wanted to make a feature film and was drawn to the story of Cas & Dylan, which is scripted by Jessie Gabe.
He said: "The movie is really about how two diametrically opposed people at two very different points in their lives, how these two very different people can still have a lot of things to teach each other and how there are a lot of things they can each learn from each other.
"For my first feature film I was looking for a film that was of a manageable size and this film felt like it was a pretty manageable size for me. For the most part it's a two hander which made it feel pretty intimate, pretty small, and it's a road movie.
"I liked the characters, I enjoyed the characters and I liked where the movie goes at the end. The movie goes to some pretty unexpected places at the end and I appreciated it for that."
He said it was exciting to get Dreyfuss on board for his first feature film.
He said: "Getting Richard Dreyfuss to come and be in the movie was really one of the things that elevated the project for all of us. Richard's inclusion in the cast of the film was a big lift for all of us and it was a really good get for us.
"He is an amazingly talented actor and a great collaborator and the work that he and Tatiana do in the movie together is really special and it really helped to elevate the film."
The trip the characters make in the film from Winnipeg to British Columbia was also a journey into the past for Priestley himself as he made it with his father when he was a child.
He said: "When I was a small boy I actually made that trip from Winnipeg to Vancouver with my father so I was very familiar with the landscapes and the hours of boredom that happen when you drive across the prairies in Canada. It's stunningly beautiful but it just goes on for days.
"I was very familiar with it and I wanted to make sure that the audience had that very visceral experience that I had had as a child making that trip."
Cas & Dylan is showing as part of the Glasgow Film Festival, which runs from February 20 to March 2.
The programme includes pop-up cinema and special events in unique venues around the city.
Priestley said: "I'm very excited to be here in Glasgow, I've never been to Scotland before which I'm kind of embarrassed about because half of my family is Scottish so I'm kind of embarrassed about the fact I've never been here before, so very excited to be here in Scotland and very excited to share the film with everyone here in Glasgow tonight."