Extracting an extra mile from every gallon of gas may not seem like a huge accomplishment. However, Mercury engineers spent a lot of time working to increase the 2009 Mariner's fuel mileage by one mpg. If you do your part by driving at or below the speed limit, avoiding aggressive acceleration, combining errands, turning off the engine to prevent unnecessary idling, avoiding time consuming and dangerous left turns, keeping your tires fully inflated, frequently replace the air filter, and making certain your Mariner is properly maintained, that measly one mpg might grow to five, seven or more additional mpg.

Here are some of the things Mercury engineers did to improve fuel mileage:

• Introduced a new 171-horsepower, 2.5-liter four-cylinder engine that employs variable intake cam timing. Performance is increased over the previous 2.3-liter engine without losing economy. The U.S. government's EPA says front-wheel-drive Mariners get 20 miles per gallon in the city and a respectable 28 mpg on the highway. Zero to 60 mph acceleration is more than 1.5 seconds quicker.
• Added a six-speed transmission to enhance performance and economy by reducing engine rpm at highway cruising speeds. Both the four-cylinder and the V6 are available with this transmission.
• Employed throttle-by-wire: called electronic throttle control by engineers. This replaces the manual linkage between accelerator pedal and the engine. It helps maximize economy and performance.
• Squeezed both 40 more horsepower and one mile per gallon from the uplevel 3.0-liter V-6 engine. Variable valve timing and electronic throttle control are keys to this improvement. For 2009, the V6 is rated at 18 city and 26 on the highway.
• Redesigned the front and side bodywork to reduce wind resistance and enhance fuel economy.
• Replaced the traditional belt-driven power-steering unit, which drains power even when driving down a straight road, with an electric-powered unit that draws energy only when the steering wheel is turned.
• Added low-rolling resistance tires in an effort to squeak out the last few yards from every gallon. Low rolling resistance tires have less traction, however, especially on damp roads.

Mercury's focus hasn't been strictly on improving fuel economy. A retuned suspension, complete with a new anti-roll bar and revised shock absorber turning gives the Mariner better traction and enhanced road feel. Refined steering system offers better feel and confidence in urgent situations.

The Mariner comes in four trim levels: the Mariner I-4 and Mariner V-6, as well as a Premier I-4 and a Premier V-6. All are available in front- or all-wheel drive. Trailer Tow Prep Package is available on the Mariner V-6 and Mariner V-6 Premier and allows these vehicles to tow trailers weighing up to 3500 pounds properly equipped.

A voice-activated navigation system is optional on the Premier models. Standard features on 2009 Mariner include cruise control, anti-lock braking system, Advance Trac® with RSC® Roll Stability Control^™, dual front airbags, front-seat side airbags and the side-curtain airbags in the Safety Canopy® System. An AM/FM system with a single-CD player is standard. Available on Premier models is an AM/FM Premium 6-disc in-dash CD changer with four speakers, SIRIUS® Satellite Radio with 6-month prepaid subscription and SYNC^™ communications and entertainment system. New for 2009, is the available voice-activated Navigation System with SIRIUS Travel Link^™.

The Mariner is also available as a hybrid. That version is covered in another article.

For 2009, Mercury Mariners come with a bumper-to-bumper limited warranty for three years or 36,000 miles (see dealer for details). Also, the five-year powertrain limited warranty covers everything from front- and rear-wheel drive components, to the engine and transmission.

The 2009 Mercury Mariner is an enjoyable-to-drive, right-sized sports utility vehicle with unsurpassed fuel economy in its class for both the I4 (20/28 mpg) and V6 (18/26 mpg) engines. If you can't have fun with it, you can't have fun.

Mac Demere is a former racecar driver who ran the NASCAR Southwest Tour and 24 Hours of Daytona.