High on Diesel

August 18, 2008

A few weeks ago, I wrote a post on extreme fuel saving measures, including ditching your gasoline-powered car for a nice, sooty diesel. I have been in love with the rumbling of diesel engines ever since I picked up my first diesel VW Golf. Even this day, the smell of diesel exhaust makes me a little giddy (although the reasons may be as much biochemical as emotional).

In addition to gobs and gobs of torque (yes, the proper unit for measuring torque is in “gobs”) and the pleasure of getting to fill up next to the big rigs at highway truck stops, my favourite aspect of diesels has always been the excellent fuel economy delivered by diesel engines. Diesel engines are notably more efficient than their gas counterparts, and even with elevated diesel prices, deliver nice savings. Just how efficient, you may ask? Well, according to Fifth Gear, that delightfully British gearhead TV show, a diesel-powered Jeep Patriot SUV delivered almost the same real-world fuel economy as the revered hybrid Toyota Prius.

Had we relied on the onboard computers, the Prius would have won by a landslide, as by the end of the trip they read 57mpg and 42mpg for the Prius and Jeep respectively.

However, to get the real figure, we calculated consumption based on how much fuel each car had used over the 160 miles. The result was astonishing: both cars had used nearly identical amounts of fuel. The Jeep had averaged 38.9 mpg – only 3.1 mpg less than its computer had recorded. However, the computer of the Prius appeared to be telling whoppers: it actually achieved just 39.9 mpg – a massive 17.1 mpg less than it had claimed.

… Our test also raises the question over the economy of hybrids overall – a subject to which we will be returning. Certainly it might feel like you’re contributing to a greener world, but most manufacturers are constantly improving their diesel cars to make them greener and more efficient. It seems that if economy is what you’re after from a family car, there are better, and – let’s face it – more stylish, options than a Prius.

Even I, a diesel fanboy, have some reservations about the methodology employed by Fifth Gear. Specifically, I would love to know the details of how they measured actual fuel consumption- was it based on fuel pump cutoff (fairly unreliable and imprecise), or a more accurate measure such as by gross vehicle weight? But even aside from these concerns, the article lends support to my pontifications that diesel vehicles offer an excellent alternative to gassers (and apparently, hybrids!) for those looking for greater fuel economy.

Unfortunately, there is a dearth of diesel passenger vehicles available on the North American market today. If you want an oil burner, your options (aside from the heavy duty trucks) are limited to a handful of Volkswagens, the Mercedes E-Class, a couple of Jeeps, and the Smart Car. Elsewhere in the world, auto makers offer a much broader range of diesel vehicles in every class. But hope is on the horizon- Honda has announced plans to bring diesel power to North America in 2009, as has BMW, and other manufacturers are working on bringing their diesel cars here as well. And in what amounts to an automotive wet dream for me, Subaru has unveiled the diesel boxer engine that will be available in the 2010 Legacy and Outback. It is almost certain that these diesel options will a bit more than gasoline versions, but I’m hopeful that the premium will be reasonable and that more people can be convinced to give diesel a shot.

{ 3 comments… read them below or add one }

Lard Black 08.18.08 at 11:55 am

I’m a bit sceptcial of the claims. Like you say, we don’t know how they measure actual fuel use. I think theMFA would be more reliable than trying to measure the amount of fuel used.

Joe @ Simple Debt-Free Finance 08.18.08 at 12:56 pm

I’m curious at what point increased demand would push the price of diesel high enough to wash out the benefits in fuel economy. Of course, more people switching to diesel would lessen the demand for gasoline which would benefit me.

Maybe you should keep the virtues of diesel quiet, and to yourself MGL. 😉

Lisa 08.18.08 at 5:17 pm

Right now diesel where I live is about $4.60 while regular unleaded is $3.89 a gallon. I cringe when I fill my TDI, but luckily those fills are only about every 2-3 weeks. Love the 50 mpg, not so loving the price of diesel right now. We also have a diesel 3/4 ton truck for hauling horses, hay etc. We never use that thing anymore unless we absolutely have to. But we keep it cause of the “gobs” of torque. That puppy could pull a house!

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