But even she could not help those who turned in to a petrol station in Wester Ross in search of a top-up for the miles to come.
The petrol station was in fact a purpose-built film set for Shell, an acclaimed new drama starring Pirrie in her first lead role.
"It was great it looked that realistic," laughs Pirrie, 25, speaking in Glasgow ahead of the city's film festival premiere of writer-director Scott Graham's picture.
Pirrie plays the titular Shell, a young woman who lives with her father in the Highlands. While dad (Joseph Mawle) tears cars apart for scrap, Shell tries to build a life out of chatting to the few customers that come the petrol station's way.
A former pupil at The Mary Erskine School in Edinburgh, Pirrie graduated from the Guildhall School of Music and Drama in 2009. Such is the long build-up between the initial idea for an independent film, pulling the money together and getting it on the screen, she first saw the script for Shell several years ago.
"I'd only been out of drama school for a few months and I got the script through my agent. I read it outside a pub I worked in at the time and I just thought, 'This is great, I know this girl, this person, I could do this.' Then I was like, 'Well I'm never going to get it but I might as well go in and do my best.'"
When she went for the audition she was heartened by Graham's attitude to the material. "That is the thing when you work with a writer-director, it is a piece of them and they really care about it. They are asking you questions and they really want to know." Though fearing she had not done well, she won the part. "At the time I thought I completely screwed up and ran into the street and cried."
Graham's debut feature, which began life as a short film, was shot at Little Loch Broom in Dundonnell, Wester Ross. Besides building a petrol station from scratch to make the setting seem as real as possible, Graham wanted the father and daughter characters to look as though they were used to living with each other and comfortable with silences. Solution: he sent Mawle and Pirrie off to a remote cottage for a fortnight.
"There was no phone signal or anything like that," recalls Pirrie, and the TV could only play DVDs. "We just got in a car and drove to this place. We went to a Tesco and got some stuff to have dinner with. It was a bit strange first of all, but the purpose of it was that we could get to know each other in order to convincingly portray two people who have spent their whole lives together.
"I don't know if the film would have been any different if we hadn't done that, but it helps just on set to not have that need to make conversation because you know each other by that point."
While shooting the film, Pirrie and the rest of the cast and crew stayed in a hotel in Dundonnell.
"The people were great, really interested in what was going on. It was a cool hotel."
Her time in Wester Ross, and working full time on a film, made a change from Pirrie's life in London, where temporary jobs fill the gaps between auditions and acting work. At the moment, she is waitressing. Like any student of acting, she was told to expect lean times between jobs. But it has been better than she thought, she says. Having gone to Guildhall when she was 18, and immersed herself in the world of drama school, she is enjoying seeing what else is out there.
"It is just one of those things where it is so strange like that. You will have success but you have to keep ticking over, not just financially but for your mind. I like to work, I need to work. I don't like the idea of just waiting for something to come along. It can be hard but at some point maybe I'll reach a point where I don't have to do that at quite the same level as at the moment."
She is getting there. Pirrie and Graham were both nominated for best British newcomer awards at the London Film Festival (the winner was Sally El Hosaini, director-screenwriter of My Brother the Devil), and Shell was up for the Sutherland Award (which eventually went to the Oscar-nominated Beasts of the Southern Wild). Besides Shell, Pirrie was seen most recently playing a politician in Channel Four's Black Mirror.
While her parents, a lawyer and a physiotherapist, backed her acting ambitions, Pirrie credits a teacher at Mary Erskine's with first steering her towards the profession.
"Most actors, if you trace it back, have somebody in their childhood who said you know what, you can do this."
Among the actors she admires, Marion Cotillard heads a list that also includes Helen Mirren, Olivia Colman, Kristin Scott Thomas and Meryl Streep. All have something "a bit different about them", she says. Now, with Shell to her name, so does Pirrie.
Shell opens in cinemas on March 15
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