The Court of Appeal has increased the jail term from 2.5 years to four years for Mercedes-Benz driver Janepob Veeraporn, 40, who killed two students in a high-speed car crash in Ayutthaya province in 2016.
The ruling initially increased the sentence to six years, with the Appeal Court finding Janepob guilty of driving under the influence of methamphetamine and causing death. However, given the man's useful testimony, the court commuted the term to four years.

The judgement overruled Ayutthaya Provincial Court's decision in July 2017, sentencing luxury car import company heir Janepob to 2.5 years in jail for reckless driving causing death. He was released on bail pending appeal.
On March 13, 2016, Janepob was driving at a very high speed when he rammed his Mercedes-Benz into the rear of a Ford sedan carrying two post-graduate students on Phahon Yothin Road in Ayutthaya's Bang Pa-in district. Thanthaphat Horsaengchai, 34, and Kritsana Thaworn, 32, died at the scene.
Despite lacking the results of a blood test to confirm the methamphetamine in his system, the Court of Appeal found Mr Janepob guilty of driving under the influence, because the traffic law does not give the benefit of the doubt to suspects who refuse blood tests for drugs or alcohol.
Karnchana Horsaengchai, a sister of one of the victim, said: "I have faith in the system, and justice has been served."