Do fuel-saving devices work?
With petrol and diesel prices at record levels, there is renewed interest in aftermarket “fuelsaving” devices and additives that claim to save you money at the fuel pumps.
A variety of aftermarket products — including fuel additives, magnets and air flow modifiers
— claim improved fuel consumption and/or an increase in power. Some make bold claims about being able to save up to 17% on your fuel bills.
Do they actually work, are they safe for your engine, or is it just snake oil peddled by salespeople hoping to cash in on consumer gullibility?
In the course of my 30-year career as a motoring journalist, I’ve tested a number of such products — including the magnet device and additives mixed with fuel — and have yet to find one that made a meaningful difference.
There were variables in the on-road testing I’ve conducted, but in one of the most scientific local tests to date, Sasol’s fuel research facility in Cape Town evaluated a number of these devices in its laboratory a few years ago. Fuel consumption and performance tests were conducted on the same car using an airflow modifier, a fuel magnet, a fuel molecule enhancer and a fuel additive.
The tests found a maximum 0.5% difference in either fuel consumption or performance, with the researchers concluding that there were no benefits to these devices and that the results fell between the 1% experimental-tolerance band.
The results established that these products delivered some placebo effect, meaning that drivers who buy these often expensive devices inadvertently adopt a more fuel-efficient driving style. The fuel saving disappears as soon as the driver forgets about the device and returns to a normal driving style
Aftermarket additives and devices that claim miraculous benefits “are typically a scam and we do not advise purchasing these”, said Sasol.
Similarly, the US Environmental Protection Agency (EPA) has tested more than 100 “fuel-saving” products and found that most devices do not improve fuel economy to any measurable degree. Only seven devices showed any improvement in efficiency, and even then, the improvement was never more than 6%.
Some of the gadgets may even damage a car’s engine or increase exhaust emissions, the EPA found.
The popular TV show Mythbusters tested several fuel-saving devices using petrol and diesel cars under controlled circumstances. Fuel line magnets, which supposedly align the fuel molecules so they burn better, were tested and found to make no difference in fuel consumption.
The non-effectiveness of these aftermarket products comes as little surprise. The obvious question is: if they worked, why aren’t car makers and fuel companies already using them given the competitive advantage it would provide?
Conspiracy theorists might argue that companies such as Sasol, Shell or Caltex want you to use more fuel and therefore buy more of their product, but this argument doesn’t wash; it would be offset by the greater market share a fuel company could capture if its product was proven to save motorists money.
Fuel companies are already mixing additives into their petrol and diesel that maximise performance and fuel consumption, as it’s a big competitive factor
Similarly, car manufacturers spend vast resources to optimise fuel economy and reduce CO2 emissions in their vehicles given what a big selling point fuel economy is.
SA’S market leader Toyota says it uses an “army” of research and design engineers, who are on the cutting edge of scientific innovation, who study every aspect of reducing carbon emissions which results in better fuel consumption.
“I can assure you that while there is a very remote possibility that something has been missed by the research engineers in their quest to minimise fuel consumption, it is very unlikely,” says Mzo Witbooi, Toyota SA Motors’ spokesperson.
“In short, we are doubtful that there are products in the market that can feasibly claim to reduce a Toyota’s fuel usage and ensure its durability and reliability,” he says.
There’s also the risk of losing your warranty if one of these products causes damage to your car. Witbooi says it is Toyota’s policy not to do blanket cancellation of warranties, but the company reserves the right to refuse a warranty claim should it be shown that a conversion or non-approved additive has led to a failure.
Technical specialist Nicol Louw, a former technical editor at Car magazine who has tested several “fuel savers”, says these aftermarket additives are all rubbish.
The bottom line is: don’t waste your money or risk damaging your engine. The best way to save fuel is to adjust your driving style; ie, drive with a lighter foot.