The Land Transport Authority (LTA) is now requiring all compressed natural gas vehicles - not just taxis - to undergo an inspection.
It said yesterday that it was concerned about the cases of two compressed natural gas (CNG) taxis catching fire recently.
There are more than 1,600 CNG private cars on the roads, and their owners will have to get their vehicles checked at an authorised inspection centre by June 9.
The checks will include a test for gas leaks and an inspection of the condition and mounting of the CNG cylinder and related components.
The expanded checks come a day after the LTA required all 950 CNG taxis to be inspected by today, or be taken off the roads.
The authority said that as of 7pm yesterday, 832 had been checked, and 74 had failed the tests.
Of these, 73 belong to operator Trans-Cab, which owns 920 of the 950, while the other is privately owned by a cabby under the yellow-top scheme. These cabs will be pulled for further investigation and rectification.
Preliminary investigations by the Singapore Civil Defence Force found that the fires involving the CNG Toyota Wish taxis on April 30 and May 22, which caused some injuries, were caused by gas leaking into the cabins that was ignited by a cigarette being lit. Both belonged to Trans-Cab.
The company told The Straits Times on Tuesday that it would offer its cabbies replacement taxis that run on diesel.
The LTA also said yesterday that the inspection regime for CNG taxis will be stricter moving forward, from every six months to three months.
The same regime will be applied to the 12 CNG public buses that are also being called up for the same ongoing checks.
Mr Koh Bee Soon, manager of CNG system supplier AutoSoon, said there could be a lack of awareness among cabbies that they should not smoke in the cabin.
The LTA said inspection notices will be sent to all private CNG car owners, and the cost of the checks will be borne by the authority.
A CNG car owner, who wanted to be identified only as Mariam, foresees no issues with the inspection. "The nine-year-old Toyota Wish is CNG equipped, but I have switched to petrol for the past six years as the CNG kit gave problems, and the gas price went up."
"When you use CNG, the pickup is also quite slow," she added.