Oh, so a Hummer is NOT greener than a Prius

Remember that post from a few months ago about a Hummer being greener than a Prius? Well, the outfit that compared those two iconic vehicles, CNW Research, has gotten its study picked up in England (where the comparison is between a Jeep Cherokee and a Prius) and Toyota is responding by calling the study "Recycled Rubbish?".

I was skeptical of the Hummer = green claim at the time, and people certainly got to talking in the comments about the post. Now Toyota steps in and says CNW is wrong on a lot of fronts, from simple factual errors to larger methodical mistakes. It's important to remember that Toyota isn't an objective bystander in the debate, but I've got to their claims make sense to me.

You can read Toyota's entire argument after the jump.
Recycled Rubbish?

CNW Marketing Research Inc. – Study on Hybrid Efficiency
A number of UK publications have recently re-presented the results of an old study by a North American marketing research agency, CNW Research Inc. This study makes some surprising and uncorroborated claims about the total environmental impact of vehicles over the complete lifecycle (i.e. production – use – recycling).

The media have picked up on one particularly eye catching claim, namely that the Jeep Cherokee is cleaner than a Toyota Prius hybrid saloon. This result runs contrary to all other research in the area.

The "results" of the CNW study

As with any model, it is critical that the methodology is valid, the assumptions are sound, and the data accurate. The CNW study makes several assumptions which undermine the conclusions arrived at. Without a scientific peer review, it is impossible to comment on any of these factors.

What is clear, however, is that the conclusions appear to be very different from the results of several other rigorous, scientifically-reviewed studies of the lifecycle impact of vehicles (e.g. Argonne National Laboratory, Massachusetts Institute of Technology).
  • Example 1: These studies conclude that the majority (80-85%) of the total lifetime energy use of a vehicle comes from the driving stage, with the remainder coming from the remaining stages of a vehicle life, whereas the CNW study shows these percentages to be reversed.
  • Example 2: Two Toyota models mentioned in the report, the Scion xA and xB sold only in the USA, are engineered with the same processes, built on the same assembly line, transported and shipped together, distributed through the same dealer network, have the same engines and transmissions, are about the same weight (within 50 lbs.), and have very similar fuel consumption ratings (one just over 35 mpg combined, the other just below 35), yet the CNW study shows the lifetime energy use of these vehicles to be very different (53 per cent).
  • Example 3: The CNW study states that hybrids require more lifetime energy than even large SUVs. Toyota's internal analysis does conclude that there is more energy required in the materials production stage for a hybrid, but that this is overwhelmingly made up for in the driving stage (the 80-85% stage), causing the hybrid to have a significantly lower lifetime energy use.
There are also basic factual errors in the report, for example CNW claim that the hybrid batteries are not recycled.

In truth Toyota and sister brand Lexus have a comprehensive battery recycling programme in place and has been recycling Nickel-Metal Hydride (NiMH) batteries since the RAV4 Electric Vehicle was introduced in 1998. Every part of the battery, from the precious metals to the plastic, plates, steel case, and the wiring, is recycled. To ensure that batteries come back to Toyota, each battery has a phone number on it to call for recycling information.

Toyota and other environmentally conscious car makers have been using life cycle assessment for many years to evaluate various advanced vehicle technologies. Toyota, along with many others, believes that the best way to judge the environmental impact of a vehicle is to do a full evaluation of all the inputs and outputs in every stage of its life. The lifetime energy use is just one of the many things to look at.

The environment and the role of the car in CO2 emissions are rightly a very important subject for debate. Toyota welcomes such debate. However, the debate is not helped by sensationalistic reporting of an uncorroborated and unrepresentative piece of marketing research carried out in North America.

[Source: Toyota]

Share This Photo X