Indonesia's new vehicle market deteriorated sharply in July, with deliveries to dealers estimated to have fallen by almost 40% to 55,100 units from 91,400 units in the same month of last year, based on data released by industry association Gaikindo.

The sharp decline came ahead of some important new model launches in the market. Toyota this week began selling the new Avanza compact MPV, the country's best-selling model, with the Innova replacement expected to follow shortly after.

The decline was severe nevertheless and reflects the broader economic slowdown in the country, as exports continue to weaken and consumers spending remains under pressure rising inflation and high interest rates.

The regional currency turmoil has hit the rupiah hard this week, with the rupiah having lost 9% of its value against the US dollar since the beginning of the year.

Cumulative seven-month vehicle sales fell by almost 21% to 581,900 units, from 733,400 units in the same period of last year.

Gaikindo has revised down further its full-year 2015 forecasts to 950,000 units, from between 1.0-1.1 million units previously.