New Delhi on Friday wrapped up a trial of draconian driving restrictions that has taken around a million cars off the roads and seen even judges and diplomats carpool, but made little obvious difference to air quality in the world's most polluted capital.

Air quality levels remained "unhealthy" on Friday, the final day of the two-week experiment in allowing private cars on the roads only on alternate days.

Delhi commuters were nonetheless positive about the scheme, which the government may adopt on a more permanent basis, although mostly because it freed up traffic on the city's usually clogged roads.

"The traffic situation in Delhi has really improved. Earlier, it used to take me nearly one hour to commute to work and back (home), but now the time has cut to half. It's such a relief," said Rohit Srivastava, a 32-year-old bank executive who had been carpooling with his colleagues and taking the metro every second day.

Autorickshaw driver Tej Bahadur Patel, meanwhile, said the reduction in traffic at least meant he was breathing less car fumes as he plied the roads.

"Less cars means less traffic jams, which in turn means we inhale less pollution," the 38-year-old told AFP, calling for the restrictions to be imposed on a regular basis.

- 'A matter of our lives' -

In a city where road rules are routinely flouted, most drivers appeared to be obeying the restrictions and many said they viewed the scheme positively.

More than 9,000 violators were, however, dealt fines of 2,000 rupees ($30), a large sum for most Delhiites.

Delhi Chief Minister Arvind Kejriwal congratulated the city of some 17 million for complying with the strict rules, and urged residents to continue driving only on alternate days, telling a news conference it was "a matter of our lives and our city".

His transport minister said the trial resulted in a 20-25 percent drop in air pollution.

Figures from the US embassy in Delhi showed PM2.5 levels were lower than on the first day of the trial, but air quality was still "very unhealthy" on Friday morning, with PM2.5 levels at 156 -- six times the World Health Organization (WHO) safe limit.

PM2.5 refers to microscopic particles that penetrate deep into the lungs and are particularly harmful to health.

The Delhi government introduced the scheme after a court ordered authorities to act on pollution levels that sometimes reach more than 10 times the WHO's safe limits.

It is part of a wider anti-pollution drive that will also include shutting some coal-fired power plants and vacuuming roads to reduce dust.

A survey of nearly 18,000 Delhiites by global petition website Change.org on Friday found on Friday that 4.5 times more people supported an extension of the scheme than were against.

- 'People are dying' -

A 2014 WHO survey of more than 1,600 cities ranked Delhi as the most polluted, partly because of the 8.5 million vehicles on its roads, with 1,400 more added every day.

India's Supreme Court has backed the scheme, dismissing a slew of legal challenges, and even top judges said they were carpooling.

"People are dying due to pollution and you are challenging it for publicity," justices AK Sikri and R Banumathi said in a ruling Thursday.

Foreign diplomats, motorbike riders and women travelling alone or with children under 12 were also exempt, although many chose to abide by the scheme voluntarily.

The city's filthy air claims up to 30,000 lives each year, according to the Delhi-based Centre for Science and Environment.

But the auto industry argued that cars have been unfairly targeted when polluting industries were mainly to blame, and says just three percent of the city's pollution is from cars, with heavy industry and other vehicles accounting for more.

A report by India's top technology institute also found that fly-ash from coal-based tandoor ovens, burning of solid waste and road dust were among the main culprits.

The city's air usually worsens in winter as cooler air traps pollutants and people light fires to stay warm.

The Delhi government will meet on Monday to discuss the success of the scheme.