While other Japanese automakers are ditching plans to bring diesels to the United States, Mazda drives on.

Robert Davis, Mazda’s product development chief for North America, said that Mazda is looking seriously at offering a low-emissions, high-mileage diesel vehicle in American showrooms. The diesel development is part of Mazda’s goal of boosting its fleetwide fuel efficiency by 30 percent by 2015.

“We’re working very hard to make the business case for diesels at Mazda,” Davis told journalists in midtown Manhattan, as he outlined the company’s green-car plans during the monthly meeting of the International Motor Press Association.

Davis was mum on which Mazda models might receive a diesel engine. But he told me that diesel’s technical advantages -- beefy torque and a mileage boost of up to 40 percent over gasoline engines -- would be best-suited to the company’s larger people movers, meaning the CX-7 (pictured) and CX-9 crossover SUVs. Today’s modern diesels, he added, would fit perfectly with the company’s “Zoom-Zoom” philosophy of high-performance, fun-to-drive cars; BMW, Mercedes, Volkswagen and Audi have all begun to offer diesel cars in all 50 states over the past year or so.

Still, Mazda’s optimism about diesel would make it something of an outlier in the industry. While diesels are huge in Europe (roughly half of all new cars are powered by the technology), they still face huge obstacles here -- not least the cost of the fuel, which has risen above that of gasoline, sometimes dramatically so.

Those hurdles have spooked American and Japanese automakers: General Motors, Ford, Honda and Nissan have publicly backed away from previous plans to offer diesel passenger cars here. Subaru is likely on the outs as well, with company officials telling me they’re focusing their green-car efforts on hybrid development instead.

Davis acknowledged those obstacles, including the cost of the fuel and the high cost of manufacturing diesel engines. Mazda, he said, is working to drive down costs for both diesel engines and their expensive emissions equipment. For one, the 4-cylinder diesel engine that Mazda is developing would not require the pricey, pollution-fighting, urea-injection systems currently required by BMW, Mercedes and Audi diesels. Those German models must carry several gallons of ammonia-rich urea solution -- which must be replenished roughly every 10,000 miles -- to neutralize smog-forming nitrogen oxides in the exhaust stream. Without the urea systems, those cars wouldn't be green enough to sell in the key markets of California and the Northeast, meaning all the states that set tougher emissions standards than the federal rules.

So it's clear that Mazda is putting the work into making an affordable, fun-to-drive diesel available stateside; what's less clear is whether there's a market for it.