Fox News report on eFuel

Frequently cited by supporters of Ethos is a report by Fox News (though note that the website on which this video is found is not itself associated with Fox). In this report, Fox News apparently endorse Ethos FR and conclude that it definitely does improve economy.

The first thing to beware of is that media reports on fuel "saving" devices are generally little better than uncontrolled testimonials, with little attempt at scientific testing. Partly this is because journalists are not normally experts in automotive technology (whereas, without boasting, I am), and partly because they are limited in time and money. For example, the Ecotek CB-26 was reviewed by the motoring correspondent of the respected Sunday Times in 2003 and highly recommended - so much so that the Times offered the device for sale to its readers. The Advertising Standards Authority was highly sceptical of the claims, and indeed Ecotek's later scientific testing proved that the true economy benefit was less than 2%, rather than the "up to 15%" promised by the Times report. (I'm sure it is just a coincidence, but the Times and Fox News are both owned by Rupert Murdoch...)

With this in mind, the Fox News report does seem heavily flawed to me. There is no attempt at all to carry out any scientific fuel consumption testing (ie under controlled conditions); instead they rely soley on emissions measurements to conclude that the product does actually save fuel. There are two problems with this:

First, emissions measurements have their own natural variability. Factors such as engine temperature, atmospheric conditions, and (crucially) catalyst temperature can all strongly influence emissions levels. In the case of the Fox test, they measured emissions on the test car then added Ethos FR and drove it for 20 miles before re-testing - so of course the catalyst was probably hotter, and so doing a better job of removing the harmful emissions. (To give the test any credibility, the test car should had been driven for 20 miles without Ethos before doing the baseline measurement.)

The second, and more important, problem is that emissions measurements are a poor guide to economy. As the test operator in the report correctly noted, very high levels of emissions (especially unburnt fuel) - caused by a faulty spark plug, for example - do imply bad economy. But on modern cars in good condition the level of unburnt fuel in the exhaust is already so low that further reductions are essentially insignificant in terms of economy. Partly for this reason, the US Environmental Protection Agency's guide to evaluating fuel "saving" devices specifically excludes emissions data such as the Inspection & Maintenance (I/M) test as evidence of effectiveness.

Given these two flaws, to me the Fox News report does not seem to consitute any proof that Ethos FR really does give fuel economy benefits.

This video, from KVBC (NBC), is merely a description of the product without any testing at all, while this one, the Fox Fame or Shame test, actually included a "testimonial" from one user reporting no benefit at all.

Perhaps especially interesting is the report by KCRA 3, which tested three vehicles. Some improvements in emissions were noted, but no gain in MPG - in fact, one of the three vehicles got significantly worse. This report from KETV in Omaha also indicated worse economy when using Ethos FR.