News that U.S. light truck sales have slowed to a crawl as gas-pinched car buyers stay out of showrooms is hitting one L.A. auto parts company hard but boosting the fortunes of another.

Superior Industries International Inc., a major supplier of aluminum wheels to Detroit, saw its stock hit a 16-year low last week as investors shied away from companies dependent on new vehicle sales.

The Van Nuys-based company derived 82 percent of its nearly $1 billion in annual revenue last year from the big three U.S. automakers. Of even more concern to investors: About 60 percent of sales came from supplying aluminum rims for the shrinking light truck market.

Meanwhile, Motorcar Parts of America Inc., a much smaller company that remanufactures alternators and starters for nearly every vehicle on the road, has seen its stock rebound from a 52-week low in April as it has surprised investors with higher-than-expected sales.

Analysts say the decision by drivers to hold on to their vehicles longer means a greater demand for replacement parts such as starters and alternators, a critical component for recharging batteries.

“There is ample opportunity for expansion,” said analyst Anthony Cristello, of BB & T; Capital Markets. “(Motorcar Parts) has well established relationships with four of the five largest aftermarket retailers and we believe results will only get better.”

The diverging paths of the two companies reflect the topsy turvy nature of the entire auto industry. New car and truck sales, with the exception of hybrid and more efficient small vehicles, are down as consumers keep their cars on the road.

That means the median age of cars on U.S. roads has been rising. It was 9.2 years in 2007, the same as 2006, but up from nine years in 2005, according to a February report by automotive consulting firm R.L. Polk & Co.

The increasing durability of all vehicles contributed to the rise, but analysts expect the trend to only increase given the slowing economy and sharply higher gas prices. And as cars get older and are driven more, the need for replacement parts rises dramatically.

Cars eight to 11 years old have a replacement rate of 4.7 percent for alternators and 3.6 percent for starters. But that number jumps to 7.3 percent for alternators and 6.2 percent for starters after 12 years.

“Consumers are showing they want to stay with their older cars a little longer than expected,” said Motorcar Parts Chief Executive Selwyn Joffe. “We don’t sit around and hope that cars break. But statistically, it’s inevitable. And that’s where we come in.”

The company posted a profit of $2.7 million for the quarter ended March 31, up from a net loss of $2.6 million for the same period in 2007. That sent its shares rising as much as 52 percent before they settled down in recent weeks. Shares closed down 3 percent July 3 to $6.81.

Meanwhile, Superior has been hit hard, despite a surprising 50 percent rise in profits in the first quarter amid declining sales. The unexpected rise was attributed by one analyst to positive results of a joint venture in Hungary, which also has benefited from the rising value of the Euro against the dollar.

Declining sales

And while the company has maintained a solid balance sheet with virtually zero debt and more than $100 million in cash it posted a 9.4 percent sales decline for the quarter.

The company attributed at least some of the decline to a United Auto Workers strike, but analysts say the shift in consumer tastes does not bode well for the company, at least for the near term.

“Roughly 60 percent of Superior’s sales are represented by light truck platforms, which are likely to experience significant production declines,” wrote Joseph Amaturo, an analyst with the Buckingham Research Group, in a research note.

The company has gone through wrenching changes before.

In 2006, Superior decided to significantly scale back operations at its two largest U.S. plants in Arkansas and Tennessee and move those jobs to a new, $3.3 million plant in Mexico.

Analysts say the more efficient factory with lower labor costs should trim production costs. The company also has been lauded for reducing dependency on Detroit. This year management projects the Big Three will only account for 72 percent of sales.

Still, to make up the sales decline the company must reach supply deals with foreign automakers, but Amaturo said that can be difficult. For example, Honda Motor Co., the only major auto company to see an uptick in first quarter sales, makes most of their aluminum wheels in-house or gets them from their established supply chains.

Moreover, even if Superior makes such a shift to smaller cars, Amaturo said, smaller diameter wheels mean smaller profit margins.

Shares of Superior closed down less than 1 percent to $16.24 on July 3.