The Mercury Mariner is a full hybrid, and it can operate as an electric vehicle at speeds less than 25mph. The 2.3-liter gasoline engine is based on the similarly sized Ford Duratec but uses the Atkinson combustion cycle, in which late-closing intake valves effectively lower the mechanical-compression ratio in order to reduce pumping losses. The effective-compression ratio is less than 9:1 at low-rpm speeds for good drivability and much higher at high engine speeds for increased efficiency and power. It develops 133 horsepower at 6,000rpm, with 129 pound-feet of torque at 4,500rpm. This is less than the standard four-cylinder engine's 153 horsepower and 152 pound-feet, but the loss of low-rpm torque is more than compensated by the electric motor, which makes its maximum torque as soon as it starts to turn.
The permanent-magnet, asynchronous AC electric-traction motor of the 2006 Mercury Mariner makes 94 horsepower between 3,000rpm and 4,000rpm, and the maximum power from both together is 155 horsepower, from 35mph to top speed. The 38-horsepower starter motor does triple duty recharging the battery pack, sometimes feeding the traction motor directly, and controlling the transmission. There is a standard 12-volt lead-acid battery to power accessories, including the remote-entry system.
The amount of power reaching the wheels from the gasoline engine and the electric motor continuously varies and is computer controlled. A continuously variable transmission (CVT) that uses a planetary gear set blends torque from the engine and motor, and it sends power to the generator as necessary for recharging the 330-volt battery pack made of 250 D-size nickel-metal-hydride cells. A network of microprocessors--a main systems controller, as well as engine, transmission, battery, brake, and four-wheel-drive-system controllers--keeps the Mariner Hybrid running, mostly smoothly. Unlike four-wheel-drive hybrids that use electric-traction motors at the rear axle, such as the, the Mariner's Intelligent four-wheel-drive system is mechanical, sending torque to the rear axle via a computer-controlled magnetic clutch and driveshaft. It operates quickly and seamlessly.
Seamless is a good word to describe the 2006 Mercury Mariner hybrid system's operation. It's smooth and quiet at around-town speeds, at which time it can be hard to tell the power source without peeking at the power display. As with other hybrids, the engine comes to a halt when the car stops for any appreciable length of time and smoothly restarts when needed. Quiet pure-electric motion is possible from a stop at low speeds, slight descents, or on level ground. It can also happen at higher, steady speeds on the highway.
Acceleration at city traffic speeds is good, thanks to the torque of the electric motor. The CVT transmission means no shifting, adding smoothness. But merging on to the highway is another story: The engine sounds unpleasantly noisy and industrial, and above 45mph acceleration, it's more leisurely. It's not unacceptable or truly slow but not as enthusiastic as it is at lower speeds.
Hybrids have a reputation as primarily city cars, as the system works best at low and medium speeds, and the 2006 Mercury Mariner Hybrid does nothing to disabuse this. We got around 25mpg on the highway and as much as 30mpg to 35mpg in favorable city driving. Our overall average was 28mpg. The Mariner Hybrid gets AT-PZEV (Advanced Technology Partial Zero Emissions Vehicle) status from the California Air Resources Bureau.
As solid as we found the power train, the same could not be said of the suspension. Soft springs gave a traditional American luxury ride on smooth roads, but stiff shocks delivered a harsh ride over poor surfaces. The soft springs also meant plenty of body roll in corners, although with its small size, its low center of gravity, and its electric power steering, the 2006 Mercury Mariner Hybrid still handles better than larger SUVs. Attention to details in suspension tuning could work wonders.Standard safety equipment in the 2006 Mercury Mariner Hybrid includes dual-stage front air bags, anti-side-intrusion door beams, the SecuriLock antitheft system, LATCH (Lower Anchors and Tethers Child) child-seat anchors, and childproof rear-door locks. Front-side and side Safety Canopy air bags are part of the Premium Package or are a $595 stand-alone option.
A three-year/36,000-mile warranty covers most parts, with a five-year/50,000-mile coverage for seat belts and air bags. There is a five-year/unlimited-mileage coverage for perforation, such as from rust. The 2006 Mercury Mariner's hybrid system is covered for eight years/100,000 miles.