The Land Transport Authority (LTA) has found no evidence of mechanical fault in a spate of "sudden unintended acceleration" cases, after four months of investigations.
The phenomenon, which causes a vehicle to pick up speed even though the driver is not pressing the accelerator pedal, has been the speculated cause of several accidents involving taxis.
The Straits Times understands that up to a dozen suspicious taxi crashes were investigated, but most drivers eventually admitted that they had stepped on the accelerator instead of the brake pedal.
Investigations into at least three other cases are ongoing. One involves a ComfortDelGro taxi which hurtled across Scotts Road on Aug 31, causing a multiple-vehicle crash which left three people in hospital.
The latest involves a Trans-Cab taxi which hit and injured a 69-year-old valet at Marina Bay Sands last Saturday.
The Trans-Cab taxi was a South Korea-made Chevrolet Epica, while most of the other taxis in the suspected cases were Hyundai Sonatas from South Korea.
An LTA spokesman said it has been "working closely with the Traffic Police, ComfortDelGro and Komoco Motors, the authorised dealer for Hyundai vehicles in Singapore, to look into the recent cases of alleged sudden unintended acceleration involving Hyundai Sonata diesel taxis".
Based on the investigations so far, "there has been no evidence of a technical fault that causes the vehicles to accelerate unintentionally".
Neither ComfortDelGro nor Komoco would comment. Trans-Cab general manager Jasmine Tan said she had not come across previous cases of unintended acceleration.
On Saturday's accident at MBS, Ms Tan said: "The driver said he did not know how the accident happened, and claimed he was in fact stepping on the brakes.
"We'll have to wait for the police to complete the investigation."
Commenting on the issue, veteran cabby Tony Pang, 66, said: "I think sometimes the floor mat gets lodged between the brake and accelerator pedal. This can be a cause."
Cases of unintended acceleration have been widely reported elsewhere. BusinessKorea, a news portal in Seoul, reported that 417 accidents between 2010 and 2014 could have been caused by it.
Cars from Hyundai and sister brand Kia accounted for nearly 60 per cent of the cases, it added.
In 2012, the South Korean authorities investigated the cases, leading Hyundai to say it would introduce a "brake pedal throttle override" function in its cars. In 2014, an in-depth investigation by national broadcaster Korean Broadcasting System found that a version of the Hyundai Sonata had a defective engine control unit that caused unintended acceleration.
Premier Taxi managing director Lim Chong Boo said: "I think the manufacturers are aware, but the incidence is minimal. In my view, I think drivers' caution is more important when we handle mechanical equipment prone to issues."