Khaki pants and TV dinners aren’t the only staples of military life that the intrepid veterans of World War II introduced into mainstream society. America can also thank the U.S. Army for giving us the Jeep.

In 1941, the military received an order of 1,500 light reconnaissance vehicles known as the Willys Model MA. An improved version, the MB, soon appeared on the front lines, but for reasons nobody knows for sure, soldiers began calling it a Jeep.

It stands to reason that as the world became ever more complex after the war, Americans embraced the elegant simplicity of this sport utility vehicle. Jeeps can go virtually anywhere, and because of their military heritage, drivers can quickly configure them — doors on or off, top up or down — to best suit the terrain.

The success of the Jeep is proof that Americans like rallying around a winner. These are the same people who think that it’s good to leave well enough alone. Take square headlights. In the late 1980s, certain Jeep models sported new square lamps instead of the trademark round ones. Loyal owners protested until new models returned to their design roots.

Then there are the dalliances with offshoot models. In 2002, Jeep executives introduced the Liberty, a four-door that was a bit smaller than the always-popular Cherokee. But as a loyal fan of Motoring+ recently wrote us, the Liberty looked a bit too cute to be a Jeep.

The problem with tweaking an American icon is that with just a slip or two, the entire brand is compromised. That’s why Chrysler’s newly designed Liberty for 2008 is a lesson in brand awareness. It’s bigger, a lot more powerful, and incorporates elements of a rugged, outdoor lifestyle that Jeep owners have come to expect.

Make no mistake about it: Professional women — the Liberty’s intended audience — don’t want to drive cute SUVs, either. “Jeep Liberty owners will balance day-to-day responsibilities with their passion for adventure as well as the outdoors,” the senior vice president for global marketing at Chrysler, George Murphy, said. “They are athletic and pursue activities that combine their various interests with their active lifestyle.”

Hands down, the biggest improvement is the introduction of the Sky Slider, a canvas top that retracts nearly the length of the vehicle’s roof. The midsize SUV market is a tricky segment; this feature, dubbed part of the company’s “Only in a Jeep” commitment, distinguishes it from the competition.

In fact, at an auto show event at which a top Chrysler executive introduced the Liberty to an outdoor audience, he insisted on opening the roof despite torrential rain. In an act worthy of being called shift-on-the-fly, he hoisted a golf umbrella up through the hole, much to the amusement of the automotive press corps.

The nifty “Trail Rated” badge is another welcome distinction. This designation feeds the yuppie desire to impress friends and colleagues with boasts that a new SUV has passed five performance tests: traction, ground clearance, maneuverability, articulation, and water fording. The particular thresholds in each category are irrelevant. The badge, along with special side vents in the hood, announces that the owner of such a vehicle loves an outdoor challenge.

There is no end to the varieties of outdoor challenges, which is why another notable improvement is the introduction of a new full-time four-wheel-drive system. Dubbed Selec-Trac II, the system utilizes sensors that redirect torque between the front and rear axles based on driving conditions.

One of the best and most refined engines in the Chrysler stable is the power plant used in the Liberty. The 3.7-liter V-6 delivers 210 horsepower as smoothly and quietly as if it were powering one of the company’s sports sedans.

The new Liberty’s final road tests before attaining full Jeep status weren’t on paved roads, of course. The company uses “traditional Jeep gauntlets” in Moab, Utah; Death Valley, Colo.; Manitoba, Ind., and Pennsylvania that put the midsize Jeep to a range of grueling endurance trials beyond the above-mentioned Trail Rated tests.

The result is that the 2008 Liberty possesses the capability to conquer some ugly terrain, even if most of its owners are young, urban professionals who use it for commuting to work. Hey, it’s a concrete jungle out there.