Four months ago, police cars with wailing sirens would have whisked her through the city.
That Yingluck's convoy is now so keen to avoid attention - it even stopped at some red lights - is a small victory for the thousands of protesters who first poured onto Bangkok's streets three months ago to try to topple her government.
For them, Yingluck, 46, is the hated puppet of her billionaire elder brother Thaksin, who was ousted as prime minister in a 2006 military coup and now lives abroad to avoid a two-year jail sentence for corruption.
For her supporters, however, Yingluck's low-key convoy shows the tactical brain of a former business executive who had proved surprisingly adept at negotiating Thailand's cut-throat politics until anti-government protests erupted in November.
Yingluck was a political neophyte when she swept to power in a July 2011 election on the back of support in Thailand's vote-rich rural north and northeast.
Despite being sometimes dubbed the "reluctant prime minister", she had been groomed for office longer than many people realise. Once there, she deployed formidable personal charm to preside over two of the most peaceful years in Thailand's turbulent recent history.
The economy motored along, but there were signs of the rampant corruption that would later fire up the protesters. In 2011, Thailand ranked 80 out of 182 countries in Transparency International's Corruption Perception Index; two years later, it placed 102 out of 175.
GAME OF ATTRITION
Interviews with government officials, diplomats, relatives and the prime minister herself reveal a resolve that suggests Thailand's seemingly intractable and often violent eight-year political crisis could endure well past Sunday's election.
The protesters have already forced Yingluck to abandon her central Bangkok offices and shuttle discreetly between desks at a half-empty military building and a heavily guarded air force base on the city's outskirts.
But while opponents say she is on the defensive, up close she appears less a leader on the run than a player in a brutal game of attrition, quietly confident she can win any election.
The protesters, drawn mainly from Bangkok's middle classes and the wealthier south, want parliament replaced by an unelected "people's council" to reform politics before any election.
They also want the resignation of Thailand's first female prime minister and the exile of her rich and influential clan, who they accuse of corrupting politics through widespread vote-buying in their poorer but populous northern heartland.
The Shinawatra family came 10th on a 2013 Forbes list of Thailand's richest with a combined fortune of $1.7 billion.
Yingluck refuses to resign and sees herself bound by duty and by law to guide a troubled nation to its next election.
"I stand for democracy not for politics," she told Reuters. "The people would like me to continue work. The election will be the final judge(ment) by the people of Thailand."
Yingluck's serene exterior can't hide Bangkok's increasing instability. On Tuesday, shots were fired at protesters besieging an army facility where she was meeting election officials. One man was wounded by a bullet and another badly beaten by protesters.
Last month, in an attempt to defuse the crisis, Yingluck dissolved parliament and called an election for February 2. But protesters have vowed to disrupt the poll, while the opposition Democrat Party is boycotting it.
Meanwhile, Thailand's anti-graft commission is fast-tracking an impeachment investigation into Yingluck's role in a wasteful and opaque rice subsidy programme.
Opponents say the multi-billion-dollar scheme is riddled with corruption and benefits landowners and local politicians more than poorer rice growers, while farmers who haven't been paid are blocking provincial highways in protest.
"She's under unimaginable pressure, but she's coping very well," said Suranand Vejjajiva, Yingluck's chief of staff. "She feels she is elected by the people and has to protect their rights and liberties."
Yingluck hails from a wealthy and sprawling ethnic Chinese family in the northern Thai capital of Chiang Mai.
Like Thaksin, 64, she was steeped in politics since childhood, accompanying her father Lert, a businessman and member of parliament, when he visited rural constituents.
Her cousin Chaisit Shinawatra, a former Thai army chief, said Yingluck's patience was a "family principle" inherited from their grandfather, a silk merchant, who knew the painstaking process by which thread was woven into cloth. "Our strength comes from our lineage," said Chaisit.
Yingluck first chose business, not politics, although she remains untested outside the family's corporate empire.
In 1991, after graduating in political science and administration, she took her first job as a trainee at a Shinawatra telephone directory business. She then joined cellular operator Advanced Info Service Pcl (AIS) <ADVA.BK> in 1999, and was made president three years later as Thailand's mobile phone market become one of Asia's fastest-growing.
Yingluck left AIS after Thaksin sold its parent company Shin Corp to Temasek Holdings Pte Ltd, Singapore's sovereign wealth fund, in a 2006 deal worth $3.8 billion that helped precipitate years of political instability.
The controversial, tax-free sale fuelled anti-Thaksin protests until the army intervened in September 2006.
Yingluck then took the helm of SC Asset Corp <SC.BK>, the family's property development firm. But politics beckoned after her brother was convicted in 2008 and left the country to avoid imprisonment.
She was not a natural politician. In 2009, even Suranand, now a top advisor, remained "dismissive of her political prospects", according to a U.S. diplomatic cable published by Wikileaks.
By the time she declared her candidacy in May 2011, Yingluck had become an influential figure within the Puea Thai Party.
She was mobbed by adoring voters while campaigning in the north and northeast, where her brother's populist policies such as cheap healthcare and microcredit had won widespread support.
"She gained more confidence when she visited rural areas," said a close advisor, who requested anonymity.
Three months later she was prime minister.
CLONE NO MORE
Her first big test was the devastating floods that engulfed swathes of Thailand's central plains and Bangkok soon after she took office. She was widely criticised for mismanaging the disaster, and pilloried on social media for wading through flooded areas in luxury rubber boots.
But according to her cousin Chaisit, a retired general, the disaster helped Yingluck forge good relations with the Thai military. Flood-relief was part of the military's effort to repair its image after a bloody crackdown on pro-Thaksin protesters in 2010.
"They worked together for the people during the floods, and that's why they understand each other better," said Chaisit, likening the relationship to two friends bound together by a life-changing experience. Before, he said, "the prime minister and the army sat at different tables".
Thaksin once famously boasted that Yingluck was his "clone". When pressed, her advisors admit she speaks to Thaksin, although they're coy about how often. "She consults a lot of people," said Suranand.
Big brother is influential, agreed Thailand scholar Duncan McCargo, but Yingluck is no meek proxy making decisions on his behalf. With cabinet appointments, for example, her refusal to "reshuffle on demand" and accept all Thaksin's choices showed Yingluck setting her own agenda, he said.
Yingluck could not have survived nearly 30 months in office without striking what McCargo calls "an elite deal" with the establishment to paper over Thailand's deep political divides and establish a kind of peace.
That deal was shattered by Puea Thai's disastrous bid to pass a sweeping amnesty bill that would have pardoned Thaksin, he said. But its "residual strength" helps explain the coup-prone military's reluctance to intervene in the ensuing chaos.
"Yingluck's diplomatic skills and personal charm have been invaluable assets in her efforts to restore and then maintain good relations with the military and other key actors," said McCargo, a professor of Southeast Asian politics at the University of Leeds.
Yingluck moved out of her Bangkok home after it was targeted by protesters. Uppermost in her mind, said advisors, was the safety of her nine-year-old son.
Yingluck insisted to Reuters that protest numbers were dwindling. "People see that the requests of the protesters are impossible under the (law) and constitution," she said. "That's why the number of supporters is getting less."
In fact, protest numbers fluctuate, with a diehard few camping out in Bangkok's streets and parks.
If re-elected, said Suranand, Yingluck will stay on for a year or more with a mandate to reform Thailand, before holding another general election. She is number one on Puea Thai's roster of party-list candidates and has no plans to leave politics.
"The ballot box doesn't solve everything - and she knows that," he said. "But at least it's the right step."