TREADING LIGHTLY; New Jeep Wrangler is a careful evolution of iconic off-roader.

Byline: BOB GRITZINGER

Remaking an icon is dangerous business-one slip and you're in reputation-repair mode for years to come. So when the time came to build the first new Jeep Wrangler since 1997-and the first since the merger of Daimler-Benz and Chrysler-those involved in the project knew they had to tread very, very carefully.

"Any time you mess with Wrangler, you run the significant risk of alienating the Jeep faithful,'' admits Jim Issner, chief engineer for the 2007 Wrangler, which goes on sale in late August or early September. "Owners say they want more space, more capability, better ride comfort, better NVH [noise, vibration and harshness control], but then they don't want you to change anything.''

Casual Jeep watchers won't notice much difference between the previous-generation Jeep, the TJ introduced as a 1997 model, and the newest iteration, dubbed JK. It still sports the same seven-slot grille, round headlamps, trapezoidal wheel wells, exposed bolts and latches, exterior-mounted spare tire-all key design cues that have distinguished the basic Jeep since the first CJ-2A crawled out of the World War II mud and onto the civilian scene back in 1945.

Jeep aficionados will spot the changes, though, starting with the greatly expanded dimensions: JK is five inches longer and five inches wider, and rides on a two-inch-longer wheelbase with a 3.5-inch-wider track. Ground clearance is better on all models, as are the critical approach and departure angles. Standard 16-inch wheels replace the previous 15-inch base wheels, with 17- and 18-inch wheels available.

Under the hood, the venerable 4.0-liter inline-six engine is replaced by a more refined 3.8-liter, 205-hp, 240-lb-ft V6. That's a gain of 15 hp at peak, with a significantly broader powerband. The former base motor, the 2.4-liter inline-four, is gone entirely.

Wrangler transmission choices include a six-speed manual gearbox or a four-speed automatic, connected to a choice of improved transfer cases (one for garden-variety Jeep off-roading, one with a 4:1 ratio for serious rock crawlers).