The CNW Marketing Research report Dust to Dust released in 2006 claims that the Hummer H1, H2 and H3 sport utility vehicle (SUV) models consume less energy per mile driven than the Toyota Prius hybrid. In the same vein, the report claims that many other large SUV models consume less energy per mile than many other smaller vehicle models.

The report analysed data on the energy used to 'plan, build, sell, drive and dispose of a vehicle' to try and capture the life cycle of the Hummer and Prius. CNW then worked out a dollars-per-lifetime-mile figure (i.e. the energy cost per mile driven).

There have since been many papers, articles and reports written that point out the flaws in CNW’s report. For example, reports from:

One of the first things that the criticisers of the CNW report often refer to is the fact that CNW will not reveal their study methodology and results in full, thus prohibiting holistic peer scrutiny. Secondly, CNW will not give more detail on the funding of the study than to say it was ‘self-funded’.

Criticisers then go on to point out the report’s key flaws such as:

1 Mileage assumptions are biased, and based on faulty data

The writers of the report calculate total energy use per mile travelled by dividing the energy cost by the lifetime mileage. They assume:

  • Hummer H3 travels 331,200 km in its lifetime
  • Hummer H1 travels 606,400 km in its lifetime
  • Prius travels 174,400 km in its lifetime.

The problem here is that Prius owners have been shown to drive their vehicles similar distances to other sedans – around 24,000 km per year. Furthermore, we’re not yet sure exactly how long a Prius life is as they haven’t been around for long enough to find out.

2 Lifetime energy costs aren’t distributed correctly

The CNW report assumptions around energy consumption within a vehicle’s life cycle seem to be incorrect; the report assumes that the most energy is consumed during the production phase of the life cycle. Critics point out firstly that the majority of energy consumption, in terms of total energy consumption over a vehicle’s lifetime, actually occurs during the time that the vehicle is being operated. Secondly, energy consumption during the production phase, even for hybrid vehicles, is a relatively small component of the total life cycle energy consumption of a vehicle.

3 Inconsistent data manipulation

Critics can point to many examples in the report where data seems to have been manipulated in an unfair and erroneous manner. One example is the heavy penalty placed upon the newer hybrid vehicle technology; the report only takes into account the number of vehicles that have been produced to date, not the total production potential when looking to assign a ‘factory cost’ to each hybrid vehicle. Unfortunately, until CNW fully releases calculation methods, it is quite difficult for critics to holistically criticise their methods.

In short, CNW’s Dust to Dust should be read with not just a grain of salt, but a handful! This statement can be made even without having full access to the ‘science’ behind the report.