Gas prices are at their lowest level in years, and that's triggered a flurry of speculation from analysts that sales of hybrids and other fuel-efficient vehicles will suffer.

That in turn has led to a few confident ripostes from car-company executives saying that isn't the case.

DON'T MISS: 2014 BMW 328d xDrive: 40-MPG Diesel Sport Wagon Reviewed

The latest comes from BMW of North America CEO Ludwig Willisch, who says fuel prices won't affect sales of the company's diesel vehicles.

Fuel prices are "not really decisive for our business," Willisch said in a recent interview with industry trade journal Ward's Auto.

2014 BMW X5 xDrive30d

2014 BMW X5 xDrive30d

BMW customers are not really swayed by changes in fuel prices, he suggested, but rather by general economic shifts, like market fluctuations on Wall Street.

It seems that BMW buyers just don't care that much about how much they pay to fuel their cars.

That's despite the spread between gasoline and diesel reaching as much as $1 per gallon in some markets.

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BMW offers quite a few diesel models in the U.S., including diesel versions of the 3 Series sedan and wagon, 5 Series and 7 Series sedans, and the X3 and X5 SUVs.

Diesels make up 47 percent of 3 Series wagons sold, and 15 percent for the X5, the carmaker says.

In 2014, 7 to 10 percent of all 3 Series, 5 Series, and 7 Series sedans sold in the U.S. were fitted with diesel engines.

2014 BMW 535d xDrive, Catskill Mountains, Feb 2014

2014 BMW 535d xDrive, Catskill Mountains, Feb 2014

The diesel models form the third leg of BMW's green-car triad, along with ActiveHybrid models and the i3 and i8 plug-in cars.

Sales of the BMW i3 have generally exceeded industry expectations, with more than 6,000 sold in just the small electric car's first eight months.

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Diesels can be considered to be on the opposite end of the spectrum from the "i" models--which feature radical styling and all-electric (i3) or plug-in hybrid (i8) powertrains.

They offer improved fuel economy, but paired with a driving experience that's much closer to what gasoline-car drivers would be used to.


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