Are Diesels Cheaper To Own Than Gas Cars? Varies By Model, Study Says

People buy green cars for many reasons: to save money and/or to save the planet.

But fuel savings don't automatically translate into cash savings.

Diesel vehicles typically cost more than comparable gasoline models, and their fuel costs more per gallon than gasoline in most North American locations.

RELATED: Fewer Gas Stations, But More Diesel Pumps, As Diesel Sales Rise

Those facts can cancel out any savings from superior fuel economy, but potential buyers have to do the math to find out if that's the case.

Research firm Vincentric conducts an annual survey on vehicle cost of ownership.

This year it found that around a third of diesels on the market--11 out of 35 models surveyed--will save their owners money on the cost of car plus fuel during five years of ownership.

Researchers found that the average diesel vehicle yields $855 in fuel savings over its gasoline counterpart, but its five-year cost of ownership is $2,754 more.

Overall oil prices have fallen dramatically over the past few months, but the price of gasoline has dropped more quickly than that of diesel--curtailing some of the financial benefit owners might expect to see from more efficient diesels.

It's worth noting, though, that diesels tend to more consistently match their EPA-rated fuel economy in real-world driving. There are many anecdotes of drivers exceeding highway mileage ratings.