Miss Rimene, 26, said she had loved cars ever since she learnt how to drive, and Miss Murray, 28, said she was doing the course for her own personal knowledge.
The eight-month certificate in automotive engineering covers a wide range.
"We do everything from services to WOFs to suspension and brakes," said Miss Milner-Hicks, 25.
They said they had had no negative reactions from others in the course, or from their families.
"We're perfectionists - we're always fixing up the boys' jobs," Miss Rimene laughed.
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• Fewer women applying for high-paying jobs in Rotorua
Their automotive tutor Tony Middlemiss said he had seen an increasing number of women taking part in the trade industry but wasn't surprised at the TradeMe figures.
"When I went through the trade it was very male-dominated but more and more we are seeing females in the motor industry, as well as in building, engineer and manual industries.
"[Females] bring a totally different approach to the work, they ask questions you didn't expect, and where they may lack in physical strength they think about how they approach [a job]."
Toi Ohomai head of department engineering technologies and construction, John Kelly, said the four women were goal-driven and had great attention to detail.
"It's a great team vibe here with no hang ups, the women are treated as equals," Mr Kelly said.
"Women are an untapped source. Where are we going to get our labour force from? Ideally they could go from here to industry, perhaps, if they wanted, to related fields such as general mechanical work or the tyre industry."
Paula Meredith, operations engineer at the Rotorua Lakes Council, has a certificate in civil engineering and a bachelor of engineering technology, and has worked for the council for 20 years.
Mrs Meredith said she wasn't surprised only 16 per cent of those applying for engineering roles were women.
"It's the way the job descriptions are written or worded, sometimes they can be intimidating, it's having a family - women put their families first . . . and it's also there's not the numbers of girls doing the training."
She said preconceived ideas also may play a part.
"I've had people ring up and ask to speak to an engineer and what they mean is speak to a man."
Te Rangihakahaka Centre for Science and Technology - a charter school for Years 1 to 10 set to open in Rotorua next year run by Te Taumata o Ngati Whakaue Iho-Ake Trust, the educational arm of Ngati Whakaue - will look to emphasise all learners to achieve their aspirations, said trust general manager Roana Bennett.
"We want to remove any preconceived concepts of male and female areas, and instead have a curiosity driven approach. We want to nurture children's innate drive to explore."
She said the idea for the school came about due to the low number of Maori taking up science at high school.
"Maori have long been explorers, scientists and developers . . . the unintended outcome is that the perception between male and female subjects becomes diminished, if not erased entirely."
The school will cover the full New Zealand curriculum but with a focus on STEM (science, technology, engineering and mathematics) subjects, which Ms Bennett said were the basis of 60 per cent of careers nowadays.
