Hong Kong authorities have vowed to investigate a mainland Chinese driver under the southbound travel vehicle scheme and may suspend his eligibility after he posted a video of himself using automatic cruising illegally in the city on social media. The Transport Department said on Friday that it had issued a warning to the driver and had notified mainland authorities about the case. It also urged Guangdong motorists under the “Southbound Travel for Guangdong Vehicles (Entry into Urban Area)”...