Fuel-Saving Devices Debunked (2024)

From the June 2011 issue of Car and Driver

The key to any hustle is a believable story. It’s no different with fuel-saving flimflams, which often claim to exploit some small, overlooked factor that automakers or oil companies don’t want you to know about. Normally, we wouldn’t give a second thought to fuel-economy hucksterism, but our dedication to journalistic inquiry—and our desire to save you a few bucks in these times of rising gas prices—found us ordering five items that promise to stretch your petro-dollar. Four of the five devices showed up, and we tested each in a Mazda 3 and a Jeep Grand Cherokee at steady speeds—35 and 70 mph—on the oval test track at Chrysler’s Chelsea proving ground. A ScanGauge II tool (www.scangauge.com), which plugs into a vehicle’s OBD II port, provided accurate average-fuel-economy measurements. The results?  Well, we hope they don’t surprise you.

DYNAMIC IONIZER
$30.00 (www.toa-corp.co.jp)
The Claim: “Simply placed in the fuel tank or air filter, the Dynamic Ionizer pellets act as a molecular Ionizer on the fuel in the tank and air on the filter. This dynamic ionizing effect energies [sic] the fuel and air at molecular level [sic] causing [sic] to be agitated as it enters the combustion chambers.”
The Result: We never had a chance to try out these magic beans. Six weeks after we received a shipping notification from pre-tsunami Japan, this product had yet to arrive.

FUEL DOCTOR FD-47
$59.99 (www.fueldoctorusa.com)
The Claim: Plugged into the cigarette-lighter socket, “the FD-47 increases a vehicle’s miles per gallon (MPG) through power conditioning of the vehicle’s electrical systems. Conditioned and clean power allows the vehicle’s electronic control unit (ECU), fuel injection and engine timing equipment to operate more efficiently.”
The Result: The modest improvement we saw is nowhere near the claim of  “up to 25 percent” more mpg and likely attributable to minor variables such as wind. Post-test, we cracked open the FD-47 to find a simple circuit board for the LED lights. Even if you could “condition” the ECU through the lighter socket, it’s unlikely  the Fuel Doctor is doing so. On the upside, it might help prevent you from smoking in your car.
35 mph: +2%
70 mph: +1%

Update: The people at Fuel Doctor take issue with our test of their product. Fuel Doctor claims that its product is meant for vehicles that are 2 or more years old. We acknowledge that our test was performed on newer vehicles and stand behind our result. If you wish to perform your own examination we refer you to Fuel Doctor’s 90-day money back guarantee. We recommend you don't bother, though. Our follow-up test, performed with help from an independent expert, supports our initial conclusion. You can read the full report on that test here.

HOT INAZMA ECO
$99.95 (www.sunautomobile.com)
The Claim: “The vehicle’s voltage will drop when electrical components are in use and when the car is under acceleration; Hyper Voltage System stores electricity to provide constant voltage to your electrical system.”
The Result: Remember the thing about a credible story? Here’s a perfect example. Accessories sap power from the electrical system. The alternator responds by pumping out more power and increasing the engine’s load and fuel consumption. The capacitors in the Hot InaZma Eco (we took a destructive peek inside) are not likely what was responsible for the negligible fuel-economy improvement we measured.
35 mph: +2%
70 mph: +1%

MOLETECH FUEL SAVER
$129.99 (www.moletech.biz)
The Claim: “Moletech is a fuel enrichment system that modifies the properties of fuel. It changes the molecular aggregation of the fuel from larger clusters to smaller clusters or even single molecules by breaking down the van der Waals force between the fuel molecules. The smaller fuel molecules expose a larger surface area for improved contact with oxygen which produces a better combustion reaction, in turn allowing greater fuel efficiency.”
The Result: The Moletech consists of three small cylinders: one for the fuel tank, one for the air cleaner, and one for a coolant line. After installation, these passive devices require an “activation,” whereby you rev the engine for a few minutes. Even if the chemistry mumbo jumbo were real, what’s to stop the fuel from clumping up again on the way to the engine? You’re better off wearing a special fuel-optimization party hat than buying the Moletech.
35 mph: +2%
70 mph: -1%

FUEL BOSS MAGNETIC FUEL SAVER
$23.99 (www.jcwhitney.com)
The Claim: “When gasoline remains in your tank over time, the fuel molecules start to cluster. The molecules on the inside of these clusters can’t be exposed to the oxygen necessary for combustion. The result is incomplete fuel burn with the unburned molecules emitted as pollution or remaining inside the engine as damaging carbon/varnish deposits. [It delivers] an abrupt designed magnetic field to break up these fuel clusters, exposing all molecules to the oxygen, ensuring the best fuel burn possible!”
The Result: Fuel readily burns when it’s vaporized, mixed properly with oxygen, and lit with a spark. Save the magnets for a bracelet that improves your golf game. For the truly gullible, the company also offers an “ultra-heavy-duty” version for $38.99.
35 mph: -2%
70 mph: -5%