The US EPA tested various types of gas-saving products. Most didn’t live up to their promises. A few—noted below with asterisks–may save measurable but small amounts of gas.
Air Bleed Devices: These devices bleed air into the carburetor. They usually are installed in the Positive Crankcase Ventilation line or as a replacement for idle-mixture screws.
The EPA evaluated the following products: ADAKS Vacuum Breaker Air Bleed; Air-Jet Air Bleed; Aquablast Wyman Valve Air Bleed; Auto-Miser; Ball-Matic Air Bleed; Berg Air Bleed; Brisko PCV; Cyclone-Z; Econo Needle Air Bleed; Econo-Jet Air Bleed Idle Screws; Fuel Max*; Gas Saving Device; Grancor Air Computer; Hot Tip; Landrum Mini-Carb; Landrum Retrofit Air Bleed; Mini Turbocharger Air Bleed; Monocar HC Control Air Bleed; Peterman Air Bleed; Pollution Master Air Bleed; Ram-Jet; Turbo-Dyne G.R. Valve.
Vapor Bleed Devices: These devices are similar to the air bleed devices, except that induced air is bubbled through a container of a water and anti-freeze mixture, usually located in the engine compartment.
The EPA has evaluated: Atomized Vapor Injector; Frantz Vapor Injection System; Hydro-Vac: POWERFUeL; Mark II Vapor Injection System; Platinum Gasaver; V-70 Vapor Injector; SCATPAC Vacuum Vapor Induction System: Econo-Mist Vacuum Vapor Injection System; Turbo Vapor Injection System.
Liquid Injection:These products add liquid into the fuel/air intake system and not directly into the combustion chamber. The EPA has evaluated: Goodman Engine System-Model 1800; Waag-Injection System*.
Ignition Devices:These devices are attached to the ignition system or are used to replace original equipment or parts. The EPA evaluated: Autosaver; Baur Condenser; BIAP Electronic Ignition Unit; Fuel Economizer; Magna Flash Ignition Control System; Paser Magnum/Paser 500/Paser 500 HEI; Special Formula Ignition Advance Springs.
Fuel Line Devices (heaters or coolers).These devices heat the fuel before it enters the carburetor. Usually, the fuel is heated by the engine coolant or by the exhaust or electrical system. The EPA has evaluated: FuelXpander; Gas Meiser I; Greer Fuel Preheater; Jacona Fuel System; Optimizer; Russell Fuelmiser.
Fuel Line Devices: (magnets).These magnetic devices, clamped to the outside of the fuel line or installed in the fuel line, claim to change the molecular structure of gasoline. The EPA has evaluated: PETRO-MIZER; POLARION-X; Super-Mag Fuel Extender; Wickliff Polarizer (fuel line magnet/intake air magnet).
Fuel Line Devices (metallic).Typically, these devices contain several dissimilar metals that are installed in the fuel line, supposedly causing ionization of the fuel. The EPA has evaluated: Malpassi Filter King [fuel pressure regulator]; Moleculetor.
Mixture Enhancers (under the carburetor).These devices are mounted between the carburetor and intake manifold and supposedly enhance the mixing or vaporization of the air/fuel mixture. The EPA has evaluated: Energy Gas Saver; Environmental Fuel Saver; Gas Saving and Emission Control Improvement Device; Glynn-50; Hydro-Catalyst Pre-Combustion Catalyst System; PETROMIZER SYSTEM; Sav-A-Mile; Spritzer; Turbo-Carb; Turbocarb.
Mixture Enhancers (others). These devices make some general modifications to the vehicle intake system. The EPA has evaluated: Basko Enginecoat; Dresser Economizer; Electro-Dyne Superchoke; Filtron Urethane Foam Filter; Lamkin Fuel Metering Device; Smith Power and Deceleration Governor.
Internal Engine Modifications. These devices make physical or mechanical function changes to the engine. The EPA has evaluated: ACDS Automotive Cylinder Deactivation System*; Dresser Economizer; MSU Cylinder Deactivation*.
Accessory Drive Modifiers. These devices reduce power to specific auto accessories. The EPA has evaluated: Morse Constant Speed Accessory Drive **; P.A.S.S. Kit**; PASS Master Vehicle Air Conditioner**.
Fuels and Fuel Additives.These materials are added to the gas tank. The EPA has evaluated: Bycosin; EI-5 Fuel Additive; Fuelon Power; Johnson Fuel Additive; NRG #1 Fuel Additive; QEI 400 Fuel Additive; Rolfite Upgrade Fuel Additive; Sta-Power Fuel Additive; Stargas Fuel Additive; SYNeRGy-1; Technol G Fuel Additive; ULX-15/ULX-15D; Vareb 10 Fuel Additive; XRG #1 Fuel Additive.
Oils and Oil Additives.Usually these materials are poured into the crankcase. The EPA has evaluated: Analube Synthetic Lubricant; Tephguard.
Driving Habit Modifiers.These are lights or sound devices to tell the driver to reduce acceleration or to shift gears. The EPA has evaluated: AUTOTHERM**; Fuel Conservation Device; Gastell; IDALERT**.
Miscellaneous.The EPA has evaluated: BRAKE-EZ; Dynamix; Fuel Maximiser; Gyroscopic Wheel Cover; Kamei Spoilers**; Kat’s Engine Heater; Lee Exhaust and Fuel Gasification EGR; Mesco Moisture Extraction System; P.S.C.U. 01 Device; Treis Emulsifier
* Indicated a very small improvement in fuel economy but with an increase in exhaust emissions. According to Federal regulations, installation of this device could be considered illegal tampering.
** Indicated a very small improvement in fuel economy without an increase in exhaust emissions. However, cost-effectiveness must be determined by the consumer for a particular application.