Sales of motorcycles and cars, the key indicators of consumer spending in Indonesia, Southeast Asia's biggest economy, tumbled in January in a sign that consumers' purchasing power has weakened.

Two-wheeler sales plunged by 13.22 per cent to 579,361 units in January in comparison with the same period last year, while four-wheeler sales dropped by 9.14 per cent to 94,139 units, according to data compiled by PT Astra International released on Tuesday, February 17th.

The soft sales followed a downward trend seen in December from earlier months. Indonesian Motorcycle Industry Association (AISI) chairman Gunadi Sindhuwinata attributed the decline to the impact of the fuel price rises in mid-November, which had pushed up staple food prices, leaving people with less disposable income.

"Although the [government] lowered the fuel price again in January, staple food prices have not dropped. So consumers are still coping with the adjustment [in prices], and buying a motorbike is not a priority," Gunadi told a daily.

Lower motorcycle sales took place across all three major brands - Honda, Yamaha and Suzuki - which saw respective declines of 7.18 per cent to 339,850 units, 19.17 per cent to 140,243 units, and 62.05 per cent to 11,389 units.

Manufacturers expected sales to rebound in the upcoming months and peak a few months before the Idul Fitri festivities. The business group has predicted that full-year sales in 2015 will be up slightly by nearly 2 per cent to 8 million units from 7.87 million units in 2014.

Meanwhile, shrinking sales occurred across key car brands - Toyota, Daihatsu, Mitsubishi and Suzuki - excluding Honda, which booked dramatic growth.

The biggest drop impacted market leader Toyota, which saw sales plunge by 24.27 per cent to 27,175 units, followed by Mitsubishi and Suzuki down by 15.21 per cent to 11,365 units and 13.64 per cent to 12,683 units, respectively.

In stark contrast Honda booked growth of 74.94 per cent to 16,855 units driven by significant surges in sales of its most popular models, such as the Mobilio, Freed and CR-V.

Association of Indonesian Automotive Manufacturers (Gaikindo) chairman Sudirman Maman Rusdi said the business group anticipated sales to be similar to last year at 1.21 million units.

"High interest rates are one of the factors that will derail growth along with slower economic expansion," he said, adding, however, that improved economic growth in the second quarter might help sales rise.