For a permit that has cost a token S$2 a month for more than three decades, the jump is steep. A single crossing will soon cost more than Malaysian cabbies have paid for a whole month of access, the LTA told CNA.

Behind the increase is one of the widest car-cost gaps in the world.

Singapore tops the cars category of Swiss wealth manager Julius Baer's Global Wealth and Lifestyle Report, which has ranked the city the world's most expensive for the wealthy three years running.

The reason is policy. A Certificate of Entitlement, the bid-for license needed to put any car on the road, can exceed S$100,000 before the vehicle itself is paid for, on top of a steep Additional Registration Fee.

The Land Transport Authority named both, along with fuel prices and the exchange rate, as the forces pushing Singapore operators' costs far above their Malaysian counterparts'.