To create this full-hybrid propulsion system, a 2.3-liter inline four-cylinder engine is matched with two AC electric motors powered by 250 D-size nickel-metal hydride batteries located in a pack that is mounted beneath the cargo floor. This combination results in the equivalent of 155 horsepower, and a regenerative four-wheel-disc braking system automatically recharges the Mariner Hybrid's batteries.

A continuously variable transmission helps to optimize fuel economy and acceleration, sending power to all four of the 2006 Mercury Mariner Hybrid's 16-inch, five-spoke alloy wheels. A light foot on the throttle and speeds of less than 25 mph result in electric-only motoring, conserving fuel and helping to boost city fuel economy figures.