This is down from 50,040 in 2010, or a drop of nearly 80 per cent in ten years.
Red-plate - or off-peak cars - cannot be driven on the roads between 7am and 7pm on weekdays. Drivers on the scheme get rebates of up to $17,000 on a new off-peak car and a $500 discount on annual road tax.
To drive during restricted hours, they have to buy a day licence for $20.
Despite the scheme's increasing unpopularity, The Straits Times understands that the authorities have no plans to do away with it. Experts, however, noted that it should not be resuscitated as it no longer fits into Singapore's overall transport policy.
Associate Professor Walter Theseira of the Singapore University of Social Sciences said the off-peak car scheme was introduced in 1994 as a way of broadening access to car ownership by making it cheaper.
It was also seen as a way to help manage congestion, he said, by keeping red-plate cars off the roads during peak hours.
Both these purposes have since become obsolete.
"Our thinking has changed over time. (We now think) that we should instead find ways to help reduce demand for car ownership by providing meaningful and better alternatives through public and shared transport," he said.
"In addition, our ability to target car usage when it causes congestion has improved substantially, with the further development of the ERP system," he added.
Prof Theseira, who teaches economics and looks at urban transport issues, said the scheme could be allowed to die a natural death.
With Certificate of Entitlement (COE) prices high, the off-peak car scheme discount matters less to price sensitive consumers. Singaporeans are also becoming more affluent, which makes them less willing to accept restrictions on their driving time.
In 2019, 2,581 drivers converted their off-peak cars to normal cars. Last year, 1,460 did so.
Singapore University of Technology and Design (SUTD) associate professor of engineering systems and design Lynette Cheah said there is also the added consideration that the off-peak car scheme is not the best use of resources.
Red-plate cars remain parked most of the time, occupying parking spaces. They also take up a part of the quota for Singapore's overall vehicle population, which has been fixed and is no longer allowed to grow.
There are also other options that could make more sense to off-peak car drivers, prof Cheah said.
"With the availability of short-term rentals, shared cars, and private hire cars, motorists or commuters looking for flexible private car use have different options."
However, Assistant Professor Raymond Ong of the National University of Singapore, who researches transport infrastructure, said there is no rush to phase out the scheme.
It remains relevant today, he said, as there are still those who only drive on weekends.
"I think it is better to keep this option open so there are choices and alternatives. However, this may decline over time as we become car-lite."