省油骗术? 有人用过这个吗?

想买怕上当受骗. 号称90 day Satisfaction Guaranteed or your money back

http://www.ebay.com/itm/2001-Toyota-Highlander-OBD-Fuel-Gas-Saver-ECU-Chip-/320563892680

OBD Fuel/Gas Saver ECU Chip

How it Works:
The FS3 uses an exclusive process of Dynamic Soft-Flashing not available anywhere else. Each FS3 comes programmed with a set of EPROM addresses that directly affect fuel efficiency. When the ECU attempts to read one of these addresses, the FS3 patches the factory value with one from its on-board highly tuned map.