NEWARK — Maria Fernandes' days were grueling, spent shuttling between shifts behind the counter at of Dunkin' Donuts at Newark Penn Station and three other jobs.

Her fatigue was often visible, as she subsisted on precious little sleep in her car or elsewhere in the hours, or even minutes, between her obligations.

“She used to work like three shifts every day,” said Parth Patel, who worked alongside Fernandes at Penn Station. “Sometimes she wouldn’t sleep for five days.”

This Friday, however, was going to be special.

The 32-year-old city resident had taken the entire day off, telling coworkers that she planned to spend it celebrating Michael Jackson’s birthday.

Fernandes idolized the late singer, and was often caught belting out his songs and mimicking his signature dance moves during her shifts. She had even purchased a cake for the occasion.

But the day never came.

Fernandes was found dead in her car Monday night in a lot off Route 1 & 9 in Elizabeth, where she had stopped for a nap earlier that day. Authorities say she appears to have been overcome by a mix of carbon monoxide and gasoline that spilled when a can she carried in the car toppled over.

An exact cause of death has yet to be determined, but no foul play is suspected.

Parth and other coworkers at the Penn Station Dunkin’ Donuts said Fernandes had been a model employee for nearly two years, much longer than an average employee's tenure.

Despite long hours at other jobs, including the chain’s locations in Harrison and Linden, they said Fernandes remained dedicated and conscientious, treating customers during her regular afternoon shift with consistent kindness.

“She was a very sweet person. A hardworking person,” said Ravina Ramjit. “She was always joking around with everybody.”

While pleasant, coworkers said Fernandes spoke little about her personal life. They learned that she had been born in Portugal, and immigrated to Massachusetts before settling in North Jersey.

Parth said she had been saving the money she earned at her various jobs, and had just recently purchased the 2001 Kia Sportage where she was found Monday night. It was unclear whether she lived alone or with others, but she often spoke fondly of animals, including dogs and cats she kept at as pets.

“She was just a nice human being,” he said. “She was everywhere, she used to do everything. And the good thing was, she never called out.”

Dan Ivers may be reached at divers@njadvancemedia.com. Follow him on Twitter at @DanIversNJ. Find NJ.com on Facebook.