The Appeal Court yesterday ordered the family of Orachorn "Praewa" Thephasadin na Ayudhya, who killed nine people and injured four others in a crash on a tollway in 2010, to pay the victims 19 million baht in compensation.
It said the driver of the van, which was also speeding when it was hit, should be held partially responsible.
In 2015, the Civil Court ordered Ms Orachorn's parents to pay compensation of just under 30 million baht, plus 7.5% interest.
Ms Orachorn rammed her car into the rear of a passenger van carrying students and staff of Thammasart University's Rangsit campus on the Don Muang Tollway on Dec 27, 2010, killing nine and injuring four others.
Ms Orachorn, who was 16 at the time and not eligible to hold a licence, was eventually found guilty of reckless driving causing death.
In 2011, she was charged with driving without a licence, reckless driving causing death and injuries, property damage, and using a mobile phone while driving.
She was sentenced to three years in prison, which was later suspended.
She was ordered to perform 48 hours of community service a year for four years as a condition of her release.
The case involved 28 plaintiffs -- all relatives of the dead and the injured.
The compensation ranges from 4,000 baht to 1.8 million baht per case.
The victims' families had earlier demanded a sum of 120 million baht and said yesterday they would decide later whether to appeal.
The court said the compensation request for Naruemol Pittatanang, who was driving the passenger van that was hit by Ms Orachorn's white Honda Civic on the night of Dec 27, 2010, was too high.
On that night, Naruemol was also driving recklessly as she drove at high speed before being rammed by Ms Orachorn's car, the court said.