Diesels deserve more appreciation for their great highway fuel economy vs hybrids

How diesel cars and hybrids compare in our tests

Published: October 09, 2013 03:00 PM

Diesels rarely get their due. Consumers looking for great mileage often overlook them in favor of hybrids. Yet for the kind of driving that many Americans do, and especially those who drive a lot of highway miles, diesels may be a better choice.

To be sure, consumers have had good reasons to avoid some diesels; until recently, all diesel cars were built by European automakers that didn’t have the best reliability track records and were often fit to pricey, upscale models. However, diesels are now starting to trickle out in a growing range of body styles from a wide variety of automakers.

The latest we’ve tested is the Chevrolet Cruze Turbo Diesel, with a base price of about $25,000. At a glance, its overall fuel economy is respectable at 33 mpg, but it is not impressive. However, the Cruze Turbo Diesel returned an outstanding 49 mpg on the highway. That’s the third best highway figure for any vehicle we’ve tested. The only cars that can beat that lofty number are the Volkswagen Passat TDI diesel (51 mpg) and the Toyota Prius (55 mpg). It is worth noting, that among those three, the Prius is a purpose-built hybrid with an ultra-aerodynamic shape, whereas the Cruze and Passat are traditional sedans with super-efficient powertrains.

Likewise, the Volkswagen Passat TDI diesel gets just 37 mpg overall, but it returns an amazing 51 mpg on the highway.

Diesels tend to get about 30-percent better fuel economy than their conventional counterparts, while most hybrids concentrate their savings in stop-and-go city driving. That’s because hybrids’ electric drive works at low speeds and reduces most gas consumption in urban environment. Highway driving doesn’t involve much of the electric assist, so the savings there aren’t so great. (Hybrids also recoup some energy by coasting and braking to fill their battery, but those instances are few and far between on the highway.) For example, the most efficient midsized sedan we’ve tested, the Ford Fusion Hybrid, gets 39 mpg overall, but it barely improves that number to 41 mpg on the highway.

For those looking for a conventional powertrain, the Mazda 6 gets the best overall fuel economy of any conventional midsized sedan we’ve tested at 32 mpg overall and 44 mpg on the highway.

Fuel-efficient cars under $30,000 CR overall fuel economy CR city mpg CR highway mpg Annual fuel cost (highway)
Toyota Prius Four 44 32 55  $764
Honda Civic Hybrid 40 28 50  $840
Ford Fusion SE Hybrid 39 35 41  $1,024
Toyota Camry Hybrid XLE 38 32 43  $977
Volkswagen Jetta Hybrid SE 37 29 45  $987
Volkswagen Passat TDI SE 37 26 51  $941
Volkswagen Jetta TDI 34 25 45  $1,067
Chevrolet Cruze Diesel 33 22 49  $980
Mazda6 Sport 32 22 44  $955
Ford Focus SE SFE 31 21 43  $977
Honda Accord LX (4-cyl.) 30 21 40  $1,050
Chevrolet Cruze Eco 27 17 40  $1,050

Even at today’s historically high prices for diesel fuel, which are running about 13 percent more than gasoline, diesels can save drivers money. Naturally, the savings increase with annual miles driven.

All this goes to show that car buyers need to be better informed than ever before, not just about how vehicles perform, but also how and where they expect to drive. City drivers may be best served by hybrids, highway drivers consider diesels. That distinction is likely to be even more important in the future, with a wide variety of plug-in hybrid configurations hitting the market.

The good news is that there are more choices than ever that can optimize fuel economy. Current diesels have become cleaner, quicker, and smoother; they don’t deserve the bad rap they used to get.

Eric Evarts

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