Hong Kong police have detained a man and woman on suspicion of perverting the course of justice after their HK$3.7 million (US$550,000) sports car slammed into the side of a flyover.

The Lamborghini Gallardo Coupe was approaching Western Harbour Tunnel on Connaught Road West at about 7am on Sunday. But the driver crashed shortly before entering, leaving the pair with minor injuries.

The woman, 39, told officers who arrived at the scene she had been behind the wheel. But after investigation, police suspect it was the 36-year-old man who was driving at the time. Both passed breathalyser tests.

They were arrested on suspicion of perverting the course of justice. They have not been charged and were released on bail, with a requirement to report back to authorities next month. They were treated for their injuries at Queen Mary Hospital.

The Western district investigation team is handling the case.

The woman reportedly bought the Lamborghini Gallardo Coupe for HK$3.7 million in 2009.

An online clip from a dashboard camera in another vehicle in the area at the time of the incident showed more than 10 sports cars racing along the road to the tunnel.