A third-time drink-driver saw his jail sentence reduced by a third - from six weeks to four - after he succeeded yesterday in his appeal to the High Court over the unusual circumstances of his case.

Having learnt his lesson from two drink-driving convictions, businessman Wang Kim Fatt had hired a valet driver to take him home whenever he went out drinking.

Wang, 53, even included the valet driver in his car insurance policy as the second driver. But after drinks one night last March, the valet asked Wang to demonstrate how to drive his new Maserati. The valet told him he was not familiar with the controls.

Wang had picked up the $600,000 GranTurismo MC Stradale from a dealer just hours earlier. The supercar does not have a gear shift; instead, the gearbox is robotised and the drive modes are activated by paddle shifters.

Wang got into the driver's seat with the valet next to him and drove for 710m before he was stopped at a police roadblock in Mayne Road, off Mackenzie Road. He was arrested after failing a breathalyser test.

Wang was initially sentenced by a district court to six weeks' jail, a $10,000 fine and an eight-year driving ban after he pleaded guilty to his third drink-driving offence.

He accepted the fine and ban but appealed against the jail term.

His lawyer, Mr Daniel Chia, argued that while six weeks' jail is within sentencing norms for the typical third-time offender, Wang's jail term should be shortened as his case was "peculiar and special".

Deputy Public Prosecutor Kong Kuek Foo argued that Wang ought to know he should not have been driving and that six weeks was in the lower range for such offences.

Judge of Appeal Chao Hick Tin agreed that the circumstances were not typical and cut Wang's jail term. He noted that Wang did make an effort to comply with the law but "a certain situation arose".

"He should have left the car in the parking lot rather than try to demonstrate to the driver how to operate the machine," said the judge.

Mr Chia said his client's decision was a "costly lapse of judgment".

He said: "The prospect of leaving the brand-new car overnight in the carpark was unpleasant."

Wang was first convicted of drink driving in 1994; he was fined $3,500 and disqualified from driving for two years. In 2006, he was jailed a week, fined $8,000 and handed a four-year driving ban for his second offence.