The car screeches to a halt and bodyguards keep back the crowds who try to touch the black-turbanned and grey-robed cleric who emerges.
Former president Mohammad Khatami, a champion of reform in Iran, gives a quiet greeting and hurries into a small mosque in the city of Islamshahr to give his only campaign speech ahead of Friday's parliamentary elections.
Hundreds of people have squeezed to fill the Al-Reza mosque to capacity, with many others forced to listen to the speech on the pavement in the low-income satellite city just outside Tehran.
"The vote is the ultimate criteria. Those who do not believe in the vote are not the friends of the people," said Khatami as he urged reformists to vote en masse in Friday's election.
"We must all take part in the election. This will allow the formation of a strong parliament to bring those who are in power to account," he added.
Many in Islamshahr, whose population swelled in past years as part of the mass migration from villages to cities, would perhaps have been natural supporters of populist President Mahmoud Ahmadinejad when he came to power in 2005.
But reformists are hoping to capitalise on the weakness of Iran's economy in recent years which has led to double-digit inflation that has hit low income families hard.
Khatami's call to vote is a defiant one -- hardliners have disqualified hundreds of reformist candidates in pre-vote vetting, effectively wrecking their hopes of wresting control of parliament from the conservatives.
Despite the failure of his 1997-2005 period in office to bring drastic change on Iran, Khatami still preaches the same message of Iranian reformism -- economic development accompanied by cautious social change.
"If Iran is to be a regional power in the next 20 years it must be an exemplary country in the region in terms of political freedoms, science technology and employment.
"This is our path! Are we going to take this route?" he asked.
The hopes of real reform were stymied by powerful hardliners and Khatami's own innate caution, yet in his resplendent clerical robes he remains a popular figure whose scholarly talk contrasts with the bombast of Ahmadinejad.
He was said to have been deeply hurt by personal attacks during his presidency and allies have said he remains reluctant to stand again in the 2009 presidential polls despite pleas to do so.
Yet he has made something of a comeback in the last months after maintaining a virtual silence since leaving power, boldly criticising Ahmadinejad's policies and the vetting power of the unelected Guardians Council.
"I would do anything for Khatami to come back to power," said one of the faithful at the rally, Doustar Deylami, 50, whose two sons are unemployed. "At least under him there was less inflation."
"Khatami has made deep changes and his report card is very positive. His presence is a necessity for progress in Iran," said student Tara Shahriar, 25.
"I agree about inflation but on the international scene the situation has been better under Ahmadinejad," butted in a young bearded man, referring to the current government's more confrontational foreign policy.
Khatami and his allies emphasise that reform must take place within the framework of the clerical system envisaged by late leader Ayatollah Khomeini and his speech is also peppered with revolutionary rhetoric.
"People want freedom, independence and the Islamic republic," he said.
Khatami, who after becoming president gave a groundbreaking interview to US television calling for a "Dialogue of Civilisations", also launched a sharp diatribe against Iran's arch enemy in his speech.
"The United States, in other words the American leaders, are the enemies of the people of the region and have committed numerous crimes," he said.
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