Car makers are vowing to clear 130,000 vehicles by year-end from back orders incurred under the first-time car buyer scheme.
Surapong Paisitpatanapong, a spokesman for the auto club of the Federation of Thai Industries (FTI), said dealers are being urged to directly contact customers about whether they still want to exercise their rights under the scheme.
Under conditions imposed by the Excise Department, buyers have to show written notification to scrap their rights and let dealers sell the cars to other customers.
"The Excise Department and car dealers have been examining the exact number of potential buyers in the scheme who intend to scrap their rights," said Mr Surapong.
"But we have to admit that the ongoing aggressive sales campaigns by car makers have led certain potential buyers to baulk at honouring their purchase orders."
The FTI said yesterday that car exports rose by 17% in September to 118,253 units as makers moved to stave off bearish local sales.
The export surge set a new record in Thailand's 25-year history of car exports, fetching 52.35 billion baht, up 7% from September of last year.
For the first nine months, car exports leapt 14.2% to 847,341 units worth 383.67 billion baht, up 7.9% by value.
Car output in September totalled 194,737 units, down 16.3% year-on-year and below 200,000 for a second straight month.
Car production for the nine-month period numbered 1.93 million units, up 12% year-on-year.
The club expects full-year production of 2.55 million vehicles: 1.15 million for export, 1.4 million for domestic sale.
Last year's output totalled 2.45 million vehicles, with 1.43 million going to the domestic market.
"It's quite tough to boost domestic sales above 100,000 cars a month, because consumer demand is shrinking and financial institutions have become stricter with their hire purchase loan approvals," said Mr Surapong.
"Now, customers must make a down payment equal to 20-30% of a car's price, compared with 0-15% in 2012."