Indonesia's tax amnesty could boost industrywide car sales by a fifth as people spend their newly declared wealth on big-ticket items, according to the local unit of Honda Motor Co.

"The car ownership ratio in Indonesia is relatively low and there's enough room for producers to sell more," Jonfis Fandy, head of sales and marketing at PT Honda Prospect Motor, said in an interview Friday at the Gaikindo Indonesia International Motor Show.

"If the tax amnesty program proves to be a success, we could see an increase of as much as 20 percent next year," he said as people crowded around the latest models at the annual expo in Jakarta.