The 3.7-liter V6 works well with the automatic transmission, delivering good reponse. The V6 is rated at 210 horsepower and 235 pound-feet of torque. Fuel economy is EPA-rated 16/22 City/Highway mpg with the manual, 17/21 mpg with the automatic.
The 2.4-liter twin-cam four-cylinder engine comes standard on the Sport model, and is only available with the five-speed manual gearbox. We found the four-cylinder with manual transmission to be a smooth combination, though we suspect it may struggle at higher elevations. Besides the lower initial cost, the 150-horsepower four-cylinder gets 20/24 mpg.
We've also had the opportunity to drive a 2005 Liberty with the new 2.7 Turbo diesel. The engine is surprisingly satisfying, combining the horsepower of a V6 (160) with the torque of a V8 (295 pound-feet) and the mileage of a four-cylinder. During a recent week of testing, we averaged about 21 mpg, including a fair amount of time offroad in low range. On the highway, the diesel Liberty becomes an easy cruiser, showing just 2000 rpm on the tach at 70 mph. Our highway mileage was close to 24 mpg, some 30 percent better than the gas V6. The Diesel is rated to tow up to 5000 pounds with the optional hitch.
The new diesel seems to suffer few of the tradeoffs associated with oil-burning engines of the past. There is practically no smoke, and very little noise or vibration. The technology is European, with a very high pressure fuel injection system that burns much more cleanly than earlier designs. There is no warm-up period before starting, because the glowplugs are electronicaly controlled. The turbocharger is an advanced design with variable-geometry vanes that delivers significant induction improvements at both low rpm and high rpm, and at high altitudes.
The Diesel gets the stronger five-speed electronic automatic, which benefits from advanced logic. The transmission, depending on throttle input, can deliver two separate second-gear ratios, a lower ratio for quicker acceleration, a taller one for smooth downshifts.
The Liberty doesn't ride as smoothly on the road as a Ford Escape, particularly over bumps and other irregularities where it bobbles a bit. Nor does it handle as well as the more car-like SUVs. Steering effort is relatively easy at low speeds for a 4×4, nice when parking. On the road, the steering is reasonably on-center, a benefit of its power-assisted rack-and-pinion design. But the long-travel off-road suspension, set up to absorb impact without being overly harsh, makes for lethargic transient response in lane-change maneuvers. That said, the Liberty rides reasonably well for a short-wheelbase 4×4. It doesn't beat the driver up as much as a Jeep Wrangler does. The wider tires of the Limited and Renegade models seem to offer more stability than the narrower tires of the Sport. We've found the Liberty handles winding Virginia backroads well and feels fine on the crowded freeways around Los Angeles.
We've found the Liberty capable of handling fairly gnarly trails. We've crossed steep ditches and gullies, where its short front and rear overhangs paid off. Its tight turning radius is helpful where space is limited, something we discovered while weaving through a stand of tightly spaced trees. We clambered over big rocks and fallen trees and slowly forded boulder-strewn creeks with 18 inches of rushing water. (Jeep says it can handle 20 inches at 10 mph.) Its traction up steep, muddy banks was impressive, with no wheelspin.
Keep in mind, however, that the Liberty is limited by just 6.4 inches of front ground clearance, about the same as a Subaru. Rocks will contact the skid plates, a sound we experienced although we suspect no harm was being done. Another aspect serious trailblazers should note is that the Liberty platform is less upgradeable than Jeep's other 4x4s, such as the Wrangler or Grand Cherokee. However, a locking rear differential is available as a factory