Fuel prices are a constant concern for drivers, and the promise of a simple plug-in device that boosts fuel economy is undeniably appealing. Enter OBD2 fuel savers – electronic modules marketed as miracle gadgets that can significantly reduce your gasoline consumption. But do these devices live up to the hype, or are they just another automotive myth? A recent lab test by the German magazine “c’t” investigated these so-called fuel-saving modules and uncovered some startling truths.
The test focused on modules that connect to the OBD2 (On-Board Diagnostics II) port, a standard interface in most cars manufactured in the last two decades. This port is typically used by mechanics and vehicle inspectors to access vehicle data and diagnose issues. The allure of these fuel savers is that they supposedly optimize engine performance for better mileage simply by plugging into this port. However, the “c’t” laboratory findings were far from promising: none of the tested devices demonstrated any ability to communicate with the vehicle’s engine control unit. In fact, they were essentially useless pieces of electronics, their only function being to blink LED lights. These devices, readily available online, were exposed as nothing more than “factory-made electrical junk.”
To further deceive consumers and create a semblance of functionality, these scam devices employ several deceptive tactics.
One tactic is the use of color-coded plugs. Vendors often suggest that buyers must select the “correct” color plug for their vehicle type. Blue or red plugs are supposedly for diesel cars, while green or yellow are for gasoline engines. Some even claim color codes exist for gas-powered vehicles. This color differentiation is entirely fabricated and serves no technical purpose.
Another element of deception is a small switch located inside most of these plug-in modules, accessible through a tiny hole in the casing, often requiring a pin or needle to operate. Manufacturers’ instructions suggest that this switch needs to be activated at specific times to enhance the fuel-saving effect. However, experts at “c’t” dismiss this as mere “busywork to distract drivers.” At best, the button might alter the blinking pattern of the LEDs, offering a false sense of interaction and control. It’s a manipulative tactic designed to prevent buyers from quickly realizing they’ve been scammed, perhaps leading them to blame themselves for not using the “switch” correctly.
Finally, to preemptively address buyer skepticism and complaints, sellers often employ the “patience game.” They claim that the automatic optimization of the vehicle’s electronics takes effect only after driving at least 200 kilometers (approximately 124 miles). This cleverly deflects immediate scrutiny, as most users won’t have driven that distance right after plugging in the device. This delay tactic provides a window for sellers before customers potentially realize the product is ineffective.
The test conclusion is unequivocal: “As expected, simple OBD2 plug-in modules do not save fuel.” While there might theoretically be minuscule room for improvement in manufacturer-optimized engine control systems, achieving even marginal gains in fuel efficiency would require significantly more sophisticated technical intervention than these basic plug-in modules offer.
Furthermore, any genuine modification to a vehicle’s engine control system that actually altered performance would need to undergo rigorous homologation for each specific vehicle type. Critically, if these fuel-saving modules were genuinely capable of interfering with the engine control system, their use while driving would likely invalidate the vehicle’s operating license, potentially leading to legal and insurance complications.
In conclusion, OBD2 fuel savers are a scam. They offer a false promise of improved gas mileage without delivering any real benefit. Drivers looking to save fuel should focus on proven methods such as regular vehicle maintenance, driving efficiently, and choosing fuel-efficient vehicles rather than relying on deceptive gadgets that simply don’t work.
