diesel car podcast

I created a podcast to discuss the potential of diesel cars in the future of the U.S. transportation mix. Rising fuel costs are leading people to reconsider their choices in vehicles, and I want to know if people would consider diesels. This is important because diesel cars will be coming back to the U.S. market after finally meeting our emission requirements.

I already know what I think about diesel cars (I mean, I drive one), so I created a survey to find out what others think about them. Do you think they're dirty? Clean? Would you buy one? Etc...

What I found out was that the perception of diesels being dirty and slow is still strong. People tend to think of big trucks or old Mercedes Turbo Diesels from the 80's spewing out soot everywhere. This influenced whether people would choose a diesel car, even knowing that it got better fuel economy. But when asked again when a diesel was as clean as a gasoline car, over 83% said they would reconsider the diesel.

This is important because it reinforces another result from the survey, that is: fuel economy and environmental impact are two of the most important aspects of a car. This suggests that diesels might be a promising alternative...but there's a problem. The price of diesel fuel has been significantly higher than gasoline in recent months, so any potential financial savings might be negated by the higher fuel costs.

To determine the savings associated with price increases, I created a basic cost analysis using a diesel fuel cost of $4.19/gal and $3.49/gal for gas. At the current diesel price, gasoline would have to drop to under $2.50/gal for diesel to be uneconomical. Alternatively, at current gas prices, diesel would have to jump to $5.85/gal. It's safe to say for now that gasoline won't drop that low (at least not accompanied by a decrease in diesel as well), or the increase in gasoline costs.

Diesels meet two critical demands for consumers, that is they have potentially lower fuel costs and do this while being as clean as a gasoline car. They also offer great opportunities for biofuels use (non food competing feedstocks, of course) since they require little to no modification. As fuel prices continue to increase and emission standards become stricter, I believe diesels will play a significant role in America.

Look for the podcast on iTunes next week! If you haven't taken the survey, it's still up. Take it here!

These Diesel Prices Are Killing Me (but I’m still doing alright)!

Two years ago, I got rid of my ’94 Toyota Camry for a nice VW Jetta TDI to take advantage of the excellent fuel economy (and torque - 250 ft-lb, heh). With the exception of taking on car payments, it was a great decision. The average fuel economy in the Camry was 23 mpg. I average about 39¹ mpg now, not too shabby.

The problem now is that diesel prices have skyrocketed to just over $4 nationwide. Here in Austin, the price average around $3.99², and has been steady for a few weeks. If I got to certain Shell stations to get B20 or to EcoWise for B99, the price will be much higher. So am I still seeing a benefit?

So at $3.99/gal for diesel and 39 mpg I spend roughly 10 cents/mile on fuel. If I were driving the Camry I would be paying 14 cents/mile. At 20,000 miles/year, I would spend $2046 and $2,826 respectively. This translates to $779 in annual savings. Of course, these numbers are very rough since these aren’t average prices for the year, and specific to my cars.

The takeaway point is gas would have to drop an entire dollar to $2.35 or diesel would have to jump to $5.55 for my car to be uneconomical to drive compared to the old V6 Camry. Keep in mind that this is assuming gasoline and diesel costs are not coupled too tightly, which probably isn’t a good assumption. I would need to look at price trends and determine how closely the prices follow each other. Maybe next week.

So, okay, I’m still coming out ahead. But that doesn’t mean that my driving habits will stay the same. As Dr. Webber mentioned in lecture, it takes more than efficiency to decrease fuel consumption. It has to be coupled with an increase in fuel cost, and I think we’re seeing that now. While I’m still coming out ahead, the amount that I’m paying keeps increasing.

I might not lay off the turbo, but the concept of making an extra trip to the store or to a far away restaurant is less appealing with higher fuel costs.

¹Conservative estimate. It fluctuates from 36 to 42.
²Tarrytown Texaco, 4/2/08

Say hello to the 2009 Jetta TDI

As American auto manufacturers struggle to deliver clean, fuel efficient vehicles, Volkswagen is set to release the 2009 Jetta TDI later this year. See here. After being suspended after the 2006 model year, the TDI is back and now passes emissions in all 50 states while still offering impressive fuel economy and performance.

TDI stands for turbo direct injection, which in short means that a diesel engine is paired with a turbocharger to boost power output while maintaining excellent fuel efficiency.

Most new "clean diesels" use some form of urea injection to clean up NOx output and a diesel particulate filter (DPF) to remove particulate matter from the exhaust. The Clean TDI doesn't use urea injection, instead making use of a NOx trap and a DPF. The engine control system will periodically change operating modes to purge the NOx catalyst.

The result is 2.0L, 4 cylinder car that achieves 140 hp and 235 ft-lb of torque with fuel economy 30 percent higher than an equivalent gasoline engine. NOx emissions are reduced by 90 percent. The dirty, noisy diesels of the 1980's are a thing of the past while new powertrains are offering a great alternative to gasoline engines.

As an example of real world diesel fuel economy check out this other blog post here. Keep in mind that numbers for a manual transmission are 25% higher on average.