There’s a saying about the world’s oldest profession, but I think scam artist is just as ancient a career as sex work. When times get tough, you can count on a shyster to get exploiting. Rising gas prices are the perfect crisis for such shady characters: a substance just about everyone needs to function subject to an incredibly volatile price fluctuations will separate fools from their money in no time.

There are all sorts of “technologies” out there claiming to improve your car’s fuel efficiency, and many of these products are holdovers from the last gas crisis. Some are harmless doo-dads but others could really mess up your day—and your engine—if you put your trust in them.

My strategy to this post was not hard: I just hit Amazon and typed in Fuel Saver and was bombarded by bullshit. There are tons of scams out there, and this is by no means meant to be a comprehensive list of them. While Americans so far seem to be resisting desperate measures to save on gas, now is a good time to remind us all that if it seems too good to be true, it definitely is. And if you’re looking for a way to actually cut down on fuel consumption, this little device can save you loads.

First up is one of the easiest to debunk products out there. The eco OBD2 (and copycat products like it) supposedly works like this: plug the eco OBD2 into your 16-pin OBD port on the driver’s side. Normally, only diagnostic tools access this port or tracking tools like those used by law enforcement or insurance companies to track driver behavior. While there’s some also fairly scammy plug-ins that look similar to the eco OBD2 that will connect to your car and send data to an app on your phone, the OBD2 has some much bigger claims.

What eco OBD2 claims to do is record your driving habits for 200 km and then make changes to how your engine operates based on that data, making your car more fuel efficient and less polluting. This is a trick only the most advanced automakers like McLaren have only recently figured out , but apparently a tiny piece of plastic nailed machine learning way back in 1996.

This being a product of the ’90s makes perfect sense. It’s the automotive scam product equivalent of a nerdy “hacker” typing away at a computer and then announcing “I’m in!” Why would a port only used for spitting out data allow a tiny piece of plastic to crack pretty much any automakers’ CPU? The security implications if this thing actually worked would be unimaginable. Luckily, it doesn’t, at all.

You know those ineffective magnetic bracelets that sites like WePatriot sell to boomers as a super secret cure “They” don’t want you to know about? This fuel saving scam is like that, but for your car. Compatible with all vehicles and both gas and diesel engines (despite both engines creating combustion in a completely different manner), one of the priciest offering on this list claims to reduce fuel consumption by 20 percent by creating... a magnetic field around... the air filter? Really?

There aren’t many YouTube breakdowns of this device, probably because it’s so obviously an overpriced scam. Here’s how the product says it is supposed to work:

If you buy this product you probably deserve to be separated from your money, but not your life: Do Not Do These Things To Your Car. The air filter and ceramic beads are very stupid but probably not dangerous. I wouldn’t trust that voltage meter box on my battery, however.

This little guy again! We actually went to the time and trouble of debunking this stupid piece of fake technology . Which made the manufacturer mad . So we debunked it even harder. That’s right, a double debunking. I guess they didn’t like Jason Torchinsky’s description of the Fuel Shark as looking “...like some forsaken blue-glowing buttplug.”

The Fuel Shark/FuelSaver has two claims as to how it works. The one on its packaging states:

... supplementing the required voltage for devices such as lights, stereos, power windows, etc. By using the Fuelshark, your car’s battery does not struggle to provide the additional power needed to operate these devices.

But last year, the president of Fuelshark, Clay Renshaw, sent Torchinsky this explanation:

Capacitors are now being used by auto makers to store and release energy in order to improve MPG. Mazda has introduced this in their SkyActive I-Eloop system using a 25 Volt capacitor. We use a 35 Volt capacitor. Article attached (Nov27 Mazda).

When Jason pointed out this was bullshit. They sent yet another, even bull shittier explanation:

An electrical noise filtering unit’s performance is measured in two ways; capacity and impedance. With regard to high frequency noises occurring as short electrical impulses, the impedance is what is most important. Low impedance in the filtering results in better noise filtering.

The Fuelshark uses a low ESR capacitor. By using this type of capacitor, we have a low impedance filtering circuit. This can accept and absorb high frequency electrical distortions. These distortions can have an effect on the electronic systems of a vehicle. Thus, the capacitor is being used as a voltage stabilizer.

Mmm, smooth electricity. That’s the ticket. Our experts found the Fuel Shark just consumed a tiny bit of energy to keep its blue light on and didn’t add anything to the vehicle or the mpgs.

Jason’s original saga with the Fuel Shark is a lot of fun and well worth revisiting .

Vortex Generators are complicated little devices, and explaining them with any real expertise is just beyond my humble liberal arts degree, so here’s how they work according to a pro:

Vortex Generators certainly are a thing and are used on all sorts of vehicles, including consumer cars. However, slapping some you bought from Amazon or 3D printed yourself on to your Mitsubishi and calling it good is likely worse than doing nothing at all, according to Popular Mechanics . These bits need to work specifically with the aerodynamic elements already present on your vehicle. If vortex generators weren’t included in your car, buying random aftermarket bumps will not give you better gas milage.

OK, I know I made fun of my liberal arts degree in the last slide, but just because I made a terrible choice in education doesn’t mean I’m stupid. No matter who you are, when you read that this product (and many copycats like it) works by “...magnetizing oil molecules, [so that] the combustion is more complete...” the bullshit alarms should be clanging away.

Oil and gas are made up of hydrocarbons which, as the name suggests, are mostly hydrogen and carbon. The only materials that can be magnetized are called ferromagnetic materials, such as nickel and iron. This is middle school science, folks! At least as a clip-on device, this one won’t risk your life or the health of your vehicle. The same can not be said for our next entry.

The Double Fuel Saver Turbonator Fan claims to increase horsepower and fuel efficiency by forcing more air into your engine. All I have to say is please, please, please do not jam a $21 piece of spinning metal into your air intake. When this piece of crap fails, all those parts are going to go tumbling into your engine, causing a much bigger problem then fuel costs.

Aqua Tune sells units for everything from motorcycles to industrial machinery, boats and aircraft. It’s not just fuel savings you experience with this piece of crap, oh no. Your engine will live longer, having been steam cleaned by the Aqua Tune, which lowers engine operating temperature by 25 degrees. Aqua Tune and other products like it have been around for years and is, and has been, a complete scam that whole time, from Popular Mechanics :

The modern-day device we tested, the Aqua Tune, uses manifold vacuum, not a calibrated pump, to dribble water into the intake. They claim the ultrasonic chamber inside the Aqua Tune unit cracks the hydrogen and oxygen apart, making your car burn the water. (No one else seems to know how to disassociate hydrogen from oxygen ultrasonically.) The Aqua Tune we tested reduced engine power and increased fuel consumption, as well as making the truck run hot.

Not to demean the concept of water/alcohol injection, which is a well-understood aircraft technology and can provide a safe power boost on highly boosted engines. But a simple vacuum-operated (although not exactly inexpensive) system has no way to add water when it’s needed—during wide-open-throttle operation—since there’s no manifold vacuum then to pull water in. And there’s little advantage to adding water when there is plenty of manifold vacuum, at part-throttle.

The absolute cojones to charge thousands of dollars for something that looks like L. Ron Hubbard’s first attempt at an E-Meter.

Think of all these products like this: Automakers are always under the regulatory gun, trying to squeeze better milage and performance out of cars. If it was as simple as putting a couple little wings on the roof, or a magnet on the fuel line, they’d likely do that already. Save your money and prevent another useless piece of plastic from entering the oceans.