Drive Time
Don't Diss Diesels
Recent spikes in the price of gasoline have turned the spotlight on hybrids and other fuel sippers. But in the flight to fuel efficiency, clean diesels are often overlooked.
By Mark Solheim, Senior Editor, Kiplinger's Personal Finance
October 21, 2005
Last summer I was blithely driving down the highway, not paying much attention to how fast I was going. As I neared the bottom of a long hill, a cop signaled me to pull over. As I glanced at my speedometer, I knew why: I was going 86 in a 65 mph zone. Oh oh.
The thing is, I was driving a Mercedes-Benz E320 CDI - with a diesel engine. The car was so powerful, so smooth and so quiet, I later told the judge, that I had no idea how fast I was going. (The skeptical judge reduced the fine and gave me a stern warning.)
Recent spikes in the price of gasoline have turned the spotlight on fuel sippers. Honda Civics, Toyota Corollas and hybrids big and small are being driven off dealers' lots practically as fast as they arrive. But in the flight to fuel efficiency, clean diesels are often overlooked. For example, the Mercedes diesel gets a combined city/highway fuel economy rating of 30 mpg from the Environmental Protection Agency. Its gasoline counterpart, the E350, gets 22 mpg.
Pros and cons
Diesel technology has come a long way since the smoky, smelly, clattering vehicles of a generation ago. In the early 1990s, there was a switch from indirect to direct injection of fuel into the cylinders at high pressure. That created more efficient engines with more torque -- the power to tow and accelerate from low speeds -- than gasoline engines of the same size. Then, a few years later, advancements in turbocharging made diesels more fun to drive.
Right now, diesel cars spew more particulates (which are tiny particles of soot) and more oxides of nitrogen (which contribute to smog) than gas engines. Also, diesel fuel costs more than gasoline. Regular gas recently averaged $2.73 per gallon, while diesel has stayed stubbornly high at $3.15 per gallon.
On the other hand, diesel engines typically burn 30% less fuel than gasoline engines of similar power. Diesels also produce lower emissions of greenhouse gases, such as carbon dioxide and carbon monoxide.
Diesel engines will burn as clean as gasoline engines when new government regulations, slated to phase in by 2007, are in place. To meet the new standards, engines will have to have better particulate traps. Plus, refiners will have to drastically reduce the amount of sulfur in diesel fuel sold at filling stations.
Although about half of cars sold in Europe are diesels, selection is still sparse here in the U.S. Some carmakers are waiting until the new standards are in place to make a push for diesels, and others are betting on gas-electric hybrids.
The number of diesel models in the U.S. is expected to double between now and 2012, predicts automotive analysts J.D. Power & Associates. But until the new standards are met, diesels can't be sold in California and in a cluster of northeastern states: Maine, Massachusetts, New York and Vermont.
Do the math
The premium for the Mercedes E320 diesel ($51,825) over the E350 ($50,825) is $1,000 (compare the typical $3,000 premium for a hybrid). At today's prices, and assuming you drive 15,000 miles a year in a typical mix of city and highway driving, you would spend about $1,573 per year filling up the E320. The annual fuel cost of the E350 gas engine sedan is $2,013. So each year, at current fuel prices, you could save $440. After a bit more than two years, you've recouped the price premium.
Plus, resale values tend to be higher for diesels, partly because diesel engines usually last longer than gasoline engines and require less regular maintenance.
Volkswagen is making the biggest push toward diesel cars in the U.S. Among 2006 models, you can get the New Beetle, Golf, Jetta and Touareg SUV as diesels (TDIs, in VW parlance). The premium for VW's TDIs is also around $1,000.
Crunch the numbers for the inherently fuel-thrifty Jetta and you still come out ahead with the diesel. Annual fuel cost for the 2-liter turbocharged Jetta is $1,637, versus about $400 less for the diesel model. So, again, it will take just over two years to get your money back at the pump.