You have to drive your car for at least 150 miles to allow the chip to understand the behavior of the engine. It will not start working immediately. It read the behavior of the engine and make changes accordingly into the engine to minimize the fuel consumption and heighten the torque and power.Yes, Effuel is 100% safe and convenient to use. There is no specialized software or tool required for installation of the device into the car and it works efficiently for the car that are equipped with fuel inject engine and made after 1996.Click Here money.yahoo.com/effuel-reviews-2021-effuel-eco-215900802.html