Compressed natural gas vehicles in Singapore
LTA guidance on CNG cylinder safety, vehicle conversion approval, identification markings, recurring system checks, and the registration restriction for diesel-natural-gas cars and taxis.
Primary source: https://onemotoring.lta.gov.sg/content/onemotoring/home/owning/ongoing-car-costs/fuel.html
CNG cylinder safety
Compressed natural gas (CNG) vehicles use cylinders whose lifespan is 10 to 20 years. Each cylinder carries a marking showing its expiry date. LTA warns that expired cylinders pose safety risks and advises owners to check periodically that the CNG system is in good working condition and the cylinders have not expired (OneMotoring, Fuel).
Converting a vehicle to CNG
Before converting a new or existing vehicle, approach an LTA-approved CNG system supplier to check whether the vehicle is suitable. The supplier submits the application through LTA's Vehicle Inspection and Type Approval System (VITAS) for assessment. If the requirements are met, LTA sends an in-principle approval letter to the supplier, who then arranges an inspection at an LTA-authorised inspection centre. LTA publishes a current list of approved CNG system specialists; check that list for current contact details (OneMotoring, Fuel; OneMotoring, LTA-approved CNG system specialists).
After a vehicle is successfully modified to run on CNG, the owner must affix the CNG system-information marking shown in LTA's guidance. LTA says the marking allows the system information to be verified during periodic inspections (OneMotoring, Fuel).
Registration restriction for diesel-natural-gas cars and taxis
From 1 January 2025, new registrations of diesel-natural-gas cars, including imported used cars, and taxis are not permitted. LTA says renewal of COEs for diesel-natural-gas cars and taxis registered before that date remains permitted. This restriction is specifically for diesel-natural-gas cars and taxis; LTA's page does not describe it as a general ban on all CNG vehicles (OneMotoring, Standard Registration).
LTA says the new-registration restriction does not apply to cars registered under the Classic Vehicle Scheme or Vintage Vehicle Scheme (OneMotoring, Classic Car Scheme; OneMotoring, Vintage Car Scheme).
CNG system inspections
Taxis and buses fitted with CNG or bi-fuel CNG systems must have those systems checked every 3 months. This system check is additional to the vehicle's periodic-inspection schedule (OneMotoring, Vehicle Inspection).
Leaving Singapore by land
The three-quarter-tank rule applies when a Singapore-registered vehicle leaves Singapore through a land checkpoint, including a vehicle running on CNG. In a petrol-CNG hybrid, both the petrol and CNG tanks must be at least three-quarters full. A driver who does not comply may be issued a composition sum of up to S$500 or prosecuted in court, and will be required to make a U-turn at the checkpoint (Singapore Customs, Three-Quarter Tank Rule).
For LTA's broader modification approval steps, see vehicle modifications. For periodic vehicle inspection intervals, see periodic vehicle inspection.
Coverage debt
- LTA's public page gives a 10-to-20-year cylinder lifespan range but does not explain how the expiry date varies by cylinder model or where every cylinder's marking is located. Check the cylinder marking and contact an approved specialist for vehicle-specific advice.
- This article does not reproduce all technical CNG system standards, supplier terms, inspection procedures or conversion documentation requirements.