NEW YORK (TheStreet) -- The yen's decline in recent years has been a big boon for Japanese exporters, especially Fuji Heavy Industries (FUJHF) , best known as the maker of Subaru cars.

Subaru's plucky line of four-wheel drive cars has been racking up impressive sales numbers against bigger, more formidable competitors. A weaker yen allows Fuji and other Japanese exporters to cut prices because costs are denominated in relatively cheap yen, while revenue is realized in U.S. dollars and other strong currencies. 

Last year, Subaru -- which accounts for 85% of Fuji's worldwide sales -- sold more than 513,000 cars in the U.S., it's sixth straight year of record sales. That was a better U.S. performance than was turned in by Volkswagen (VLKAY) , whose parent is challenging Toyota Motor (TM) - Get Report for bragging rights as the world's No. 1 automaker. The Subaru brand also sold more vehicles in the U.S. than better known brand names like BMW (BAMXF) Mercedes-Benz, Lexus, Mazda (MZDAF) , GMC and Ram.

Investors have certainly benefited from this rapid growth. Fuji Heavy's common stock has soared 552 percent in Tokyo trading since 2012, when the Japanese government began engaging in fiscal maneuvers that caused the yen to depreciate against other currencies. American investors have seen Fuji Heavy ADRs jump 342 percent during the same period.

Subaru expects unit sales in the U.S. to climb 5% in 2015, which would be its seventh annual record and push North America sales volume close to its 2020 target. 

Fuji recently raised its forecasts for sales, operating profit and net income for the fiscal year ending March 31, 2015. The company expects net income to rise 22% to 253.0 billion yen ($2.11 billion) on an 18% surge in sales to 2.85 trillion yen ($23.76 billion).

It isn't just the weaker yen that has fueled Subaru's success. Its impressive growth in the U.S. was also helped by a corporate decision in 2007 to lower the list prices of its cars rather than offer steep discounts at the retail level. "Dealers and customers don't like cars that are overpriced," said Michael McHale, a spokesman. "They're bad for residual values as well."

The automaker had also replaced a third of its U.S. dealers since then.

A new Subaru marketing and advertising initiative attempted to discover the characteristics and personalities of owners who "loved" their cars, then pitch the brand to others like them, McHale said: "We built the brand around love."

That may sound a bit goofy and trite -- but, evidently, the campaign resonated.

Subaru's claims of reliability, durability and value were confirmed this week as Consumer Reports issued its influential list of best-in-class cars for 2015. Subaru's Impreza small sedan, Legacy midsize sedan, and Forester compact SUV made the list. (McHale noted that Subaru only makes seven models and thus won every category on the list for which it had an entry.)

Subaru's models are 100% all-wheel-drive, a niche that has proven popular in mountainous states and in the Northeast. Investors in the stock should keep an eye on other automakers and future all-wheel-drive models -- which could dilute Subaru's appeal. They should also stay alert for a strengthening yen, a shift that would likely hurt Fuji's financials.

This article is commentary by an independent contributor. At the time of publication, the author held no positions in the stocks mentioned.