Auto sales rose for the first time in more than 2 1/2 years in November, on an annual basis, but the increase appears to reflect coming tax changes more than an improvement in domestic demand.
Last month, auto sales rose 4.6% from a year earlier, the first such gain since May 2013, the Federation of Thai Industries said on Tuesday.
Southeast Asia's second-largest economy has yet to regain momentum after last year's coup. Exports remain weak and domestic consumption has been crimped by low farm prices and high household debt.
Thai domestic vehicle sales traditionally are sensitive to tax and subsidy policies. In 2012, during which subsidies were high, unit sales jumped 81% from a year earlier.
Last month, sales of "pickup passenger vehicles" tripled from a year earlier to 12,583. Taxation on such vehicles will increase in 2016 as Thailand seeks to encourage increased use of fuel-efficient cars.
In November, demand for passenger cars and pickup trucks still declined on-year as the economy has not recovered and banks are still cautious about lending, the FTI said.
For all of 2015, sales will be down, for the third straight row. In the first 11 months, they fell 11.9% from a year earlier.
For 2016, the FTI expects an annual increase of 3%.
"Next year, sales may not grow much as commodity prices will still be low, curbing economic growth," said Surapong Paisitpattanapong, spokesman of the FTI's Auto Industry Club. "We don't know how fast public investment will be, while private investment is not recovering."
Auto exports were down 4.6% in November, but are up 7.6% for January-November and are on course to meet the FTI's target for a record 1.2 million cars this year.
Thailand is a regional vehicle production and export base for the world's top carmakers. The automobile industry accounts for 10% of the economy.
The state planning agency has forecast economic growth of 2.9% this year and 3.0-4.0% next year. Growth last year was 0.9%.