The effects of eco mode vary depending on the manufacturer, but in general, it makes some power from the car temporarily unavailable to enhance the gas mileage. Most manufacturers state the eco mode increases fuel economy 5 to 10 percent. These gains could also be realized by practicing more conservative driving in a car without an eco mode.
The Chevrolet Equinox's eco button does not affect the throttle response, but it does make the transmission shift into a higher gear at lower speeds than usual to save gas. The Dodge Caravan evens out the throttle response and, like the Equinox, upshifts more quickly. In Honda's hybrid cars, the economy mode reduces power to the air conditioning system while keeping the lowest possible engine speed. The Kia, Hyundai and Infiniti eco modes all change the transmission shift point. As an available feature, the Infiniti offers gas pedal feedback that pushes back on the driver's foot when the accelerator is firmly depressed. Several Toyota and Lexus models have eco modes that slow the accelerator response and reduce power to the HVAC system. The Nissan Leaf and Toyota Camry hybrid also reduce power to the HVAC system, and the Leaf enhances the regenerative braking in eco mode.