SINGAPORE - A revised version of a scheme to persuade business owners to replace their old, pollutive diesel vehicles is gaining traction.

As at the end of September, 3,212 vehicles had been replaced under the Early Turnover Scheme (ETS) after it was enhanced in March.

Parliamentary Secretary for Transport Muhammad Faishal Ibrahim revealed the figure in response to a parliamentary question from MP Ang Wei Neng on Wednesday.

Dr Faishal said the number represented 77 per cent of the total number of vehicles replaced under the scheme since it began in April 2013. He added: "The increase in ETS take-up is encouraging."

When an ETS-eligible vehicle is deregistered, its certificate of entitlement (COE) does not go into the next COE quota for bidding. Instead, it is tied to the replacement vehicle, when the owner pays a pro-rated premium.

"This means that the owners can purchase a new vehicle without having to bid for a fresh COE," Dr Faishal noted.

He added that not channelling the COE of a deregistered ETS-eligible back into the bidding pool "may appear on the surface" to reduce the number of COEs available for commercial vehicle buyers.

"However, at the same time, it makes available an additional COE outside of the bidding system, and thus also takes demand out of the system," he said. "So we should not be unduly worried if there are low quotas available for bidding."

Mr Ang also asked how the scheme had affected COE prices, but Dr Faishal said it was hard to say. He explained: "The price of COEs is determined by many other demand and supply factors, such as the prevailing economic conditions and the vehicle statutory life remaining."