Mtech Inc. introduces its Moletech Fuel Saver at the 2008 Consumer Electronics Show (CES 2008).

The Moletech Fuel Saver is an universal system that can deliver fuel savings and emission reduction to all fossil fueled engines.
Mtech's molecular technology incorporates Molecule Reaction Technology to reduce fuel usage and decrease harmful emissions.
Key features include: Saves up to 20% on gasoline, Saves up to 10% on diesel, Improves horsepower, Reduces harmful exhaust pollutants, and Lasts for more than 10 years.

Sounds like snake oil, but apparently California Environment Engineering has tested it says it works, but the tests are not over a long period of time yet.
In July 2007, the California Environment Engineering (CEE) Center for Environmental Research tested the Moletech Fuel Saver using Federal Test Procedures (FTP).

Results from the CEE concluded, "Analysis indicated a reduction in key tailpipe emissions and an increasing improvement in fuel economy using the Moletech Fuel Saver device. This included a significant reduction in Total Hydrocarbons (THC) and Carbon Monoxide (CO). The results of the limited but decisive test series is considered noteworthy and verifies with a high level of confidence the viability of the technology, while indicating that more dramatic improvement could be expected and achieved with time. The device, as tested, provided results that are more dramatic than similar technologies previously evaluated."

The Moletech Fuel Saver is a universal product that can be easily installed in any fossil-fueled vehicle including automobiles, motorcycles, diesel engines, trucks, fleet vehicles, agricultural vehicles, and boats. The Fuel Saver is available in eight different models for all vehicles from scooter to semi vehicles.

A Moletech fuel saver kit for petrol engines under 3.0 liters sells for $229.99. Proceed with caution, I have no idea if this stuff really works.
Via the Moletech site.