Eight Japanese automobile manufacturers suffered historic falls in their output, exports and sales in the first half of this year, following the global economic crisis.

In June, however, the performance of the car makers varied widely depending on whether they had best-selling eco-friendly vehicles on offer.

Toyota Motor Corp. and Honda Motor Co. have overcome their slump to an extent as their hybrid cars sold well due to government’s tax breaks and subsidies for the purchase of eco-friendly cars. In sharp contrast, Suzuki Motor Corp. and Fuji Heavy Industries Ltd. continued to suffer declines in June.

Automakers’ strategy for eco-friendly vehicles is likely to emerge as a decisive factor for their business performances in the entire business year ending in March 2010.

Eight major auto manufacturers made a combined 3,223,085 cars for the domestic market from January to June, down 44.2 percent from a year earlier. This is the first time since 1990 that the number of cars the companies produced has fallen below the 4 million mark over a six-month period.

This is attributable largely to curtailing output over the January-March period as the global recession deepened. Toyota’s domestic production almost halved compared to last year’s numbers, falling to its lowest level since 1976 — the earliest year for which data is available.

Despite the setback, the Toyota group — which includes subsidiaries Daihatsu Motor Co. and Hino Motors Ltd. — remained the world’s No. 1 car maker in terms of vehicles sold worldwide.

Worldwide, the Toyota group sold 3,564,000 vehicles in the first half of this year, down 26 percent from the previous year but still topping No. 2 company General Motors, which sold 3,552,722 vehicles.

All eight firms suffered year-on-year decreases in their output in June. Nevertheless, Toyota, Honda and four other companies riding the eco-friendly vehicle boom managed to put the brakes on declines in their sales last month.

In particular, Toyota resumed operations of some of its factories on weekends and national holidays, which it had suspended in December last year, as the company has been flooded with orders for more than 240,000 “Prius” hybrid cars.

Some workers of Yamaha Motor Co. are on loan to a hybrid car battery factory that Toyota and Panasonic Corp. jointly established to respond to the growing demand.

Toyota’s domestic production in June came to 251,171 vehicles, down 31.2 percent from the corresponding month of last year — an improvement of more than 10 points from the 41.9 percent year-on-year decrease in May.

Thanks to brisk sales of its own hybrid Insight and compact Fit, Honda too saw a lower drop in year-over-year output from May to June, with a 12 point difference between the two months.

In sharp contrast, Suzuki and others that produce mainly smaller vehicles are still struggling because they gain little benefit from the government’s tax breaks for eco-friendly vehicles.

Suzuki’s output for the domestic market in June fell 35 percent in June from a year earlier, 2.3 points more than the figure for May.

“We’ll continue to curtail output for the time being,” said an official of Suzuki’s public relations division.

Meanwhile, Nissan has increased the number of cars subject to tax breaks in a bid to put the brakes on the decrease in their sales, which saw only a 2.1 point improvement from May to June.