German Diesel

One of the many perks of being a professor is that we get to choose where we spend our summers. I often take my family to the home of soccer, beer, and renewables – Germany. The place has changed quite a bit from 40 years ago. The potato fields I used to traverse on my BMX bike are covered in Chinese made Solar PV installations, there are windmills everywhere and the smell of high sulfur coal wafting across the iron curtain is absent.

While cruising down the Autobahn, you notice the extraordinary share of Diesel powered passenger vehicles. 48.1% of new passenger vehicles sold in Germany were Diesels, up from 14.6% in 1995. The corresponding Diesel share of new vehicle sales in the US is below 1%. For most Americans the only experience they had with Diesel technology is maybe their uncle’s 1970s Mercedes 300D, which smelled of fryolator grease and had Grateful Dead Stickers on it. Oh boy has that technology come a long way.

Diesels have several advantages over traditional (Otto powered) combustion engines. Most notably, they are more fuel efficient, have lower emissions of the global pollutant CO2, and they have a tremendous amount of torque. For those of you who don’t read Car and Driver every night, torque is loosely correlated with how fast your car accelerates. A little Diesel powered VW Golf GTD has the same torque as a V6 Ford Mustang, at more than 40+ mpg on the highway. In short, you get a more fuel efficient and more fun car by simply switching from a regular combustion engine to a Diesel engine.

Downsides you ask? Diesels, all else equal, have a higher price tag. For a VW Jetta expect to pay about $4,000 more, which is stiff. In Germany Diesel is taxed less heavily than regular gasoline, which gives it a pretty significant cost advantage per gallon. In California the price of Diesel and Gasoline are almost the same according to the EIA.

Further, Diesels used to have a bad reputation for their high emissions of soot and other particulates. The “new Diesels”, which are equipped with relatively expensive urea filter technology and powered with ultra low sulfur Diesel do not suffer from this disadvantage. A quick survey of some EPA testing data on representative vehicles indicates that they are not worse and in many cases better in terms of emissions of local pollutants.

I am cautiously optimistic about the role of Diesels in improving the overall fleet fuel economy. They provide another alternative to those drivers who do not want to be seen in a Prius, enjoy Mustang-like torque, and seek good fuel economy.

Why am I cautious? We have not seen how these engines hold up in terms of emissions of local pollutants, which cause things like asthma and other pulmonary diseases. Smog checks are only required for vehicles older than 4 years. The “new Diesels” have not been allowed in California for long enough for us to see Smog Check results. Further, if these cars are driven for a decade or more, it would be interesting to see how the trajectory of local pollutant emissions compares to that of regular combustion engines. Finally, if the US market went the way of the European market with half of new cars sold being Diesels, we would likely run into refining capacity constraints for Diesel.

But personally, I am going to Diesel down the road once the lease on my current Otto engine is up.

Photo Credit: German Diesel/shutterstock