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Detailed Review

# 1 - Hydrogen Gas Savers
Rating:
Overall Cost: $50-150

These work by splitting water into "HHO Gas" which is basically Hydrogen and Oxygen separated from each other. Most people are reporting results of 20-45% increases in fuel efficiency. I've also personally tested this setup and got great results. Hydrogen gas savers literally blow the other gas mileage devices reviewed out of the water. This is not a commercial snap on product, you will need to mount the water fuel cell under the hood somewhere, but that is really easy, it will be about the size of a coffee thermos. (I used zip ties actually, hah!)

Where to Buy:
#1 - Run Your Car with Water
Best Price, excellent quality! This is a very comprehensive product that is easy to follow and understand.
#2 - Water4Gas
More expensive, but also a very high quality product.
#3 - HydroStar
This kit includes the same core information as the other 2, but is not near as comprehensive and is a little hard to follow.

All 3 of the above products have a 60 Day Money Back Guarantee.

"Click Here For A Detailed Review Of The Top 3 Hydrogen Gas Savers "

# 2 - Performance Chips
Rating:
Overall Cost: $400+

There are several Performance Chips available which can not only add horsepower to your vehicle, but also improve gas mileage. These work best with high performance gasoline engines and diesel engines. I have nothing bad to say about the performance chips, other than that they can be quite pricey and generally will require installation and dyno-tuning by a professional performance shop, which itself can be quite pricey. That being said, they DO work. Horsepower increase is the most noticeable with these, but they average around 3-5mpg increase.

Where to Buy:
Local "Offroad" Performance Stores

# 3 - Turbonator/Vortex Devices
Rating:
Overall Cost: $20-50

Here is a product which I have actually had marginal success with. The "Turbonator" and similar knock-off products basically cause a spinning motion in your air intake hose, which in most cases allows the air to travel faster to the intake manifold. They are easy to install, and they do work to a certain degree, but in my tests I've noticed a maximum increase of 3 horsepower and no noticeable difference in gas mileage on average, which is far under the projected results. Because it's so quick and easy to install, I tested this on 5 different vehicles with similar results from each. It gets an E for effort, and 2 Stars only for the fact that I was able to get +3hp out of it.

Where to Buy:
eBay
Turbonator.com

# 4 - Mass Air Flow/IAT Module
Rating:
Overall Cost: $.10-10

There's not really a common name for these, but they are usually a very small box with a couple wires available on various spots on the net for $5-$15. The basic idea is that you will plug this into your Mass Airflow (MAF) sensor or Intake Air Temperature (IAT) sensor, and it will fool your cars computer into thinking that the air coming into the engine is colder than it actually is. This is done using nothing but a resistor that you can buy at Radio Shack for less than a dollar, and that's it! It DOES work in the sense that it fools your computer, but it doesn't improve gas mileage. Whether it improves power is debateable too.

Where to Buy:
DON'T! I still consider this a ripoff and a waste of time, but if you really want to try it, heres how to do it for pocket change (the cost of the resistor). (Trust me, you'll want that 5 minutes of your life back somewhere down the road)
IAT Mod

# 5 - Fuel Magnetizer
Rating:
Overall Cost: $10

These inexpensive devices can be had for around $10, and will do absolutely nothing for your gas mileage. You'd be much better off putting that $10 into your gas tank. This is an extremely tiny gadget that you basically clamp onto to your fuel line and you should magically get better fuel efficiency. The idea is that perfectly placed neodymium magnets will align the fuel molecules, and "supercharge" or "ionize" them. Scientifically speaking, that makes no sense! Feel free to try if you're curious, but I don't recommend them at all.

Where to Buy:
eBay

# 6 - Electric Supercharger
Rating:
Overall Cost: $40-90

The electric supercharger is designed behind the idea of forced induction modifications such as belt driven superchargers or the popular turbocharger which is powered using exhaust flow. While the idea is great in theory, I have yet to see one with a motor capable of pushing air near as fast as the engine is already consuming it. In other words, these tend to actually SLOW down the flow of air into the engine which can not only cause worse fuel economy (not the best feature for a gas mileage device eh?), it can also damage your engine by causing a rich fuel to air ratio! Dyno tests on a 1998 S-10 V6 indicated a 7hp LOSS and an average loss of 3mpg. If I could have found a way to graphically represent a negative amount of stars for the rating on this, you'd most definitely be looking at it.

Where to Buy:
eBay