Motorists who upload videos of illegal car races online to boast of their driving skills are helping police catch offenders.
Officers say that as front-view cameras on cars become more common, a trend has emerged for posting videos of high-speed races online.
Some of the YouTube clips show the licence plate numbers of vehicles, and reveal routes that were previously unknown to police.
Superintendent Alan Chan Hoi-lun, from the police's traffic branch headquarters, said officers regularly monitored online videos to catch racers.
"These videos provide us with much information, some we may not know - like car plates and new routes - which allowed us to trace [people] and plan our future operations," he said.
Officers are cracking down on races, which are illegal on public roads, after the number of complaints rose in the first 10 months of this year to 226, up by 11 per cent from the same period last year.
Of the 226 complaints, 11 were confirmed to be cases of illegal car racing and 35 drivers, aged from 19 to 49, were arrested.
Apart from acting on complaints, police also mounted 234 operations this year and detained 222 cars for examination, some of which were illegally modified. No casualties were recorded.
Inspector Ngai Chun-yip, from the traffic taskforce in New Territories North, said car races tended to occur in small groups and were impromptu, unlike the well-organised events of the past, and the vehicles involved usually reached speeds of between 120 and 130km/h, and not more than 150km/h. Popular spots included Fanling Highway, Tuen Mun Road and Tolo Highway.
Aside from monitoring videos posted online, police have also used roadblocks and unmarked cars with speed detectors to try to curb the enthusiasm of these street racers.