Wednesday, September 23, 2015

Diesel Deception : An Ode to the Volkswagen Jetta

During my time in the United States, colleagues and I would greatly enjoy discussions on diesel cars. Like, why weren't there enough of them in the U.S already? We knew diesel fuel holds about 12% more heat energy than the same amount of gasoline. In general, that meant, a diesel takes you farther with lesser fuel than a similar sized gasoline engined car. The Jetta happened to be everyone's favorite postercar for these discussions.

A comparison of a 2013 VW Jetta, with a 2.0L turbocharged engine running diesel and a 2.0L turbcharged Mitsubishi Lancer running premium gasoline shows stark differences. For roughly similar curb weights and passenger compartment volumes of 94 cu.ft, the U.S Department of Energy tells us that Jetta gives a 32 miles per gallon in combined city/highway compared to the Lancer's 20 miles to the gallon.

It also takes $43 to fill up a Lancer compared to $37 to fill the Jetta. Over a 5 year life cycle, compared to an average new car, you end up saving $2000 in fuel costs with the Jetta but you end up spending some $3000 more with the Lancer. What this also means is that you won't be complaining about the Jetta purchase 3-5 years down the road, as you'll end up breaking even (initial cost to fuel savings) at some point in that time frame.

Another point we are told is that both upstream in the fuel development cycle, and downstream, at the tailpipe, GHG emissions are lower in the Jetta than the gasoline Lancer. Below is the comparison from that same year, in grams of CO2 equivalent emissions (CO2 + Methane + NOx).

The EPA Smog Rating represents the amount of health-damaging and smog-forming airborne pollutants the vehicle emits. New vehicles are equipped with a sticker that shows the relative level of smog causing emissions created by the vehicle compared to others on the market. Smog-causing emissions include unburned hydrocarbons (HC) and oxides of nitrogen (NOx). Scoring ranges from 1 (worst) to 10 (best).

Those against diesel vehicles like to claim that diesel cars are nasty smog emitters. However what I find is that both the 2013 and 2014 VW Jettas appeared to have achieved the U.S EPA Smartway certification for reduced smog.

The Lancer may not have been the most ideal car to compare with the Jetta but I'm much given to my salesmanship when I think about diesel cars. They just makes sense in a world of climate change!

And so friends and I would chat about why there weren't more diesel cars, about gasoline fuel subsidies, higher priced aftertreatment emissions requirements and so on and so forth. Made for a good water cooler conversation.

With cars like Jetta being somewhat of a jewel among a bevy of polluters on our roads, it must come as a shock that possibly everything I wrote earlier about it's emissions ratings might be wrong.

The NYT has been running the story as the "diesel deception", where admittedly, senior executives from VW told EPA officials, hot on the chase for over a year, that inconsistencies in emissions values between pre-sale vehicle testing versus on-road numbers was because of a software trick.

I'm not aware of what VW actually used but the engine software in question recognized the onset of a test cycle and kicked into action for a better behaved engine performance. Typically, this involves a manipulation of the timing of fuel injection relative the movement of the piston. In normal driving, this software can be deactivated, allowing the car to tradeoff fuel economy for more pollution.

From a reading of this article, an unlikely set of heroes have emerged in discovering the fraud - a group of ex-EPA officials from the International Council on Clean Transportation who elected a research group at West Virginia University headed by Arvind Thiruvengadam, an Indian PhD in Mechanical Engineering, to test a small bunch of diesel cars on the road all in the name of science.

The ICCT is lucky to have chosen 2 out of 3 vehicles it proposed to WVU to be Volkswagens. Thiruvengadam's team, knowing how diesels should perform on the road from past testing experience, raised the red flag when they noticed anomalous postings. According to the article, some emissions values were apparently greater than those from heavy duty trucks. A baseline testing by a group from CARB would confirm the fraudulent emissions values and give credence to the WVU observation.

In the United States, emissions standards are managed by the Environmental Protection Agency (EPA) to the Federal Tier II specifications. The state of California has special vehicle emissions standards (CARB limits), and other states may choose to follow either the national or California standards.

Around 14 U.S states have adopted the CARB standards. It's instructive to compare the Federal emissions limits against the CARB limits to see the difference in stringency.

Under the 2004-2014 California LEVII motor vehicle missions, vehicles are restricted to the following numbers :

EPA's Tier II limits for light duty vehicles are the categorized into bins as the following :

From the two charts, I notice that a LEV II certification (in NOx for example) is equivalent to Bin 5 certification from the federal Tier II chart, while California SULEV certification is approximately equivalent to federal Bin 2. This is truly the case. California is extremely stringent in emissons.

Several other news articles on the same scandal state that the that Jetta posted values exceeding the U.S. NOx emissions standard by 15 to 35 times. The VW Passat was 5 to 20 times the standard.

Going purely off these numbers, I can place a low and high end ranges for what the researchers may have noticed during testing. I will assume the Jetta and the Passat were both 2014 models :

If these ranges are correct, the actual emissions performance of the VW Jetta places it in between an older/expired Bin 10b-10c and a Bin 11 vehicle category at the low end and entirely off the emissons charts at the high end.  The Passat would be between a Bin 8 and a Bin 10a category at the low end and off the emissions charts on the high end.

A momentary reflection of the fact that the greenhouse warming potential of N2O is over 300 times that of CO2 and that VW cars emitting several times their regulated values were sold and operated throughout the world for several years now will bring the gravity of the matter to light.  

That VW was trying to attain more fuel economy on the road by turning off the software is not a big surprise to me.  Engine OEM's have been doing some ridiculous things in the recent past to meet the U.S Federal Tier II and CARB regulations. From personal experience in diesel engine design, exhaust gas recirculation to combat NOx flies in the face of everything they told us about positive engine delta P, which is one in several factors affecting brake specific fuel consumption.

Specific to diesel engines is the PM vs NOx tradeoff, where if you do one thing in your combustion process to reduce NOx (typically with cooler temperatures), you start to see PM increase and vice versa. This is just an example in modern diesel engine design of a balancing act between several different parameters. Today's diesel engines are several thousand dollars more expensive than older ones because of several aftertreatment devices and control systems crammed in between engine and tailpipe. Manufacturers have to keep getting innovative year on year to meet stringent limits.

However, short of feeling sympathetic, VW still deserves a wider explanation to it's audience. To me, there are several other engineering and management decisions that could have been taken as emissions strategies. A case in point was during the roll into EPA 2010 emissions limits, when Cummins choose to adopt Selective Catalytic Reduction in their diesel engines versus Navistar shunning SCR and sticking to EGR. Cummins won with their technology solution, while Navistar failed to comply with the limits and paid $3700 fines on each non-compliant truck engine.

Precisely who in VW signed off on rigging the tests out of all other options beats me.  How did they even justify the risks that this involved, both financially and market reputation wise? These and similar corporate responsiblity type questions were posed by two Schulich business school professors Crane and Matten on their blog as well. 

The fallout could be huge. Volkswagen Jetta, for a long time, has been a reasonably priced small family car running one of the most efficient combustion engines around. However several people are going to sell their Jettas after the recall. The resale value on this vehicle will plummet like a rock. 

You can't discount the fact that that people will start to lose a bit of faith in the diesel engine itself. A market that's already straining to make grounds on a stage full of petrol cars might be looking at more struggles ahead. At the moment, we have few breakthrough engine technologies to meet environmental limits while staying commercially viable. With the VW scandal, one piece of the solution turnS out to be no solution at all, atleast in the eyes of the average Joe.

The bright side to this news is that organizations like EPA and several others around the globe will find out a method to defeat violators on the road. Maybe some new working groups will be formed to formulate off-cycle engine tests to cross-verify with dyno results. Perhaps some new independant agencies will form to assist customers in this verification. The stage is open for discussion.

Automotive safety is closely linked to the formation of such groups. The very reason why Ralph Nader brought about the National Traffic and Motor Vehicle Safety Act in 1966 was because of alleged design flaws in the suspension system of the 1959 Chevrolet Corvair. Before that fiasco in which a few people were even killed, the Corvair would go on to be named "Car of the Year" in 1960.

In another case with very close resemblance to the VW software hack, EPA had taken a group of diesel engine manufacturer's to task in 1998 for cheating during the FTA test cycle. What is strange to me is that the same problem has come to bite them now and it was a public university that first documented the issue. I fully expect a justice department hearing to call up EPA officials demanding an explanation to this oversight.

Perhaps now is the best time for some VW executives to read up on these pages in history.

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