With oil and gas prices falling, may shoppers are turning back toward units that may not be quite as fuel-efficient, but diesel fuel remains pricey.

Still,  gas prices aside, some diesel vehicles — especially luxury units — are more cost-effective than their gasoline counterparts, according to a report from Vincentric.

In its most recent Diesel Analysis, the company found that 11 out of the 35 diesel vehicles analyzed (or, 31 percent) had a lower total cost-of-ownership than their closest all-gasoline powered counterparts. Vincentric made this assertion after measuring total cost-of-ownership using eight different cost factors: depreciation, fees and taxes, financing, fuel, insurance, maintenance, opportunity cost and repairs.

The analysis assumed vehicle ownership of five years and 15,000 annual miles of driving.

Though the results may still be surprising, the number is down from 46 of the diesel vehicles measures as cost-effective in November of 2013.

“We’ve observed gasoline prices falling more rapidly than diesel prices over the past several months, reducing the fuel economy advantages inherent in many diesel vehicles,” stated Vincentric president David Wurster. “In spite of this, nearly a third of the diesels analyzed showed cost-of-ownership savings, signaling to consumers that cost savings are specific to certain models.”

Of the 11 that turned out to be especially cost-effective, 10 were luxury models; four from Mercedes-Benz and three each from BMW and Audi. And with 12 luxury diesel vehicles included in the entire study, 83 percent were cost-effective, Vincentric analysts explained.

For example, those who bought the 2014 Mercedes-Benz GL350 will save $7,789 on ownership costs, while those that bought the 2014 BMW X5 Diesel would save an estimated $2,358.

Mainstream brands didn’t fair quite as well, as Chrysler’s Ram ProMaster Diesel was the only non-luxury vehicle to have lower ownership costs than its all-gas counterpart.

According to the study, buyers were shelling out an average price premium of $5,390 for a diesel vehicle this year, with average fuel savings of $855.

The study also indicated that the 2014 Mercedes-Benz GL350 BlueTEC would save diesel owners the most on fuel, with $4,060 in savings.

And though it seems luxury buyers may want to consider diesel units for their next purchase, the overall results still show diesel vehicles may be a bit more pricy for consumers down the road.

For all 35 vehicles studied, the average cost-of-ownership was $2,754 more for a diesel vehicle compared to its all-gas counterpart. This is up $1,737 from the previous study.