Jeep engineers have kept the momentum rolling by making timely improvements.Model year 2007 brings an all-new Jeep Wrangler that (no surprise) looks just like the old Jeep, whatever 'old' Jeep you might be talking about.Can you name one vehicle (besides the Harley) that has changed its looks less, in 60 years?

In 2007, Jeep introduces its first four-door, using the name Unlimited from last year's stretched two-door.You might wonder what took them so long.It's a perfect fit for the times.It doesn't change or pervert the character of Wrangler at all, it just makes the vehicle more attainable, and more desirable for many.It's much more comfortable and convenient, and holds way more stuff, including happy passengers.

Maybe best of all, a lot more content has been added, especially in the areas of comfort, safety and convenience; and there has been an average price reduction of $1200 down the line.

Each of the six models of the Wrangler uses the same new engine, a 3.8-liter V6 making 12 more horsepower than the previous trusty inline-6 that's been around for more than 20 years.It has the same peak torque but at a higher range, and that detracts some from the Wrangler's uphill performance; but gas mileage is about the same, at 16 city and 19 highway for the 4x4.The standard transmission is a six-speed manual, which fits the Wrangler's personality quite well; the optional four-speed automatic overdrive is for those who appreciate convenience more than aesthetics.

The Wrangler X ($18,105) comes with the basic soft top, theft deterrent system, 16-inch steel wheels, rear folding seat, locking glove box, 12-volt auxiliary power outlet, tilt steering wheel, and six-speaker sound system with MP3 input.

Options include the versatile Sunrider soft top ($250), a new three-piece modular hard top ($945), air conditioning, Sirius Satellite Radio, six-disc DVD player with MP3 outlet, 368-watt Infinity sound system, remote entry and power locks and windows, and, for the first time in a Wrangler, power windows and locks with remote entry.There are also a Dana 44 rear axle, Trak-Lok anti-spin differential, 16- or 17-inch aluminum wheels, electronic front sway bar disconnect, trailer tow group, tow hooks, engine block heater, and locking fuel filler cap.

The Sahara ($19,345) is the premium model in the lineup, and adds the Sunrider top, the electronic stability program, electronic roll mitigation, 17-inch aluminum wheels with Goodyear Wrangler tires, body-colored fender flares, tubular side steps, heavy-duty suspension, tinted windows, cruise control, foglamps, tow hooks, and the Infinity sound system.Options include all the X options, 18-inch aluminum wheels, and an infotainment system with navigation, using a 20-gigabyte hard drive and DVD video-audio capability of storing 150 hours of music or probably a zillion photos.

The Rubicon ($26,090) is the model for serious off-roading.To the Sahara, it adds the disconnecting front sway bar, Rock-Trac part-time transfer case with 4:1 low range, Dana 44 front and rear axles, Tru-lok locking front and rear differential, 4.10 axle ratio, rock rails, and 32-inch B.F.Goodrich Mud Terrain tires on 17-inch aluminum rims.

The four-door Unlimited X comes with either two-wheel drive ($19,750) or four-wheel drive ($21,750).Standard equipment includes all that the two-door X offers, plus a Dana 44 rear axle, 23-gallon fuel tank, air conditioning, 60/40 split rear seat, full-length floor console and colored fender flares.It offers all the options as the two-door X and two-door Sahara, plus seat-mounted side air bags.

The Unlimited Sahara two-wheel drive ($24,075) and four-wheel drive ($26,075) is equipped like the two-door Sahara, except its power doors and windows are standard.

The Unlimited Rubicon ($28,235) might be considered the ultimate family 4X4, and for $28,895 it will carry four people where any Land Rover or Hummer can go, for about half the price.

Standard safety features include side impact door beams, anti-lock brakes and an energy-absorbing steering column.The Sahara models offer electronic stability and electronic roll mitigation.Seat-mounted front side air bags are optional with some models.

Identifying a new Wrangler Unlimited is easy: Just count the doors.

Although the wheelbase of the '07 Wrangler has been stretched by 2 inches, the vehicle is 2.6 inches shorter overall, thanks to reduced overhangs and new bumpers.And it's 5.5 inches wider, with a 3.4-inch wider track.Jeep says it's 'dramatically brawnier,' but we'd say that's a dramatic statement.The sheetmetal is new, with a slight crown.The halogen headlamps are brighter, and the new front bumper has integrated fog lamps near its center.For the first time, there are step assists under the doors to make climbing up into the Jeep easier, and the tail lamps are new.The fender flares are bolted on, so they can be easily taken off and replaced with cooler aftermarket flares.The bumpers, step assists and fender flares are all sturdy, flat-black plastic on the X.

The standard soft top is improved for easier removal and installation.The Sunrider soft top slides back half way, like a huge sunroof over the front seats.The new optional three-piece modular hardtop (Freedom Top) has two front panels that easily pop on and off like a T-top, and are stored behind the rear seat.The third panel over the rear seat can be removed separately and stored in the garage.The Freedom Top yields a total of six open-air possibilities.

Under the body, there's a new boxed frame that's 100 percent stiffer in bending and 50 percent stiffer in twisting, with seven cross members.This helps in crash results, and enabled a new suspension: steering geometry, shock absorbers, springs and control arms are all different.Wide spaced frame rails cradle the fuel tank between the wheels.Three skid plates protect the fuel tank, transfer case and automatic transmission oil pan.

The cabin is 20 percent quieter, thanks to better isolation from new body mounts, extensive use of something called PCL (polymer constraint layer), and new seals at the doors, along the A-pillar, and at the top of the windshield.

As for the larger Unlimited, Jeep claims that its 86.7 cubic feet of cargo space with the rear seat folded flat (the headrests flip back, so they don't need to be removed) is more than the Toyota FJ Cruiser, Hummer H3 or Nissan Xterra.In the rear seat, the Unlimited offers 1.6 more inches of leg room and a whopping 12 inches more hip room.That huge difference is because in the regular Wrangler, the rear passengers sit directly over the axle and between the wheel wells; in the Unlimited, the axle is located behind them.Think about how much that improves the ride for those passengers.

The layout of the clean instrument panel is excellent, against a background of dull (neither flat nor gloss) black plastic.The instruments, including the optional compass and temperature gauges, are easy to read, and the controls are soothingly simple.The solid square buttons look good and are easy to understand and operate.There's a nice leather-wrapped four-spoke steering wheel, with a short cruise-control stalk that's out of the way on the right side.

Our Sahara was equipped with the 368-watt Infinity sound system with Sirius Satellite Radio, and we bought a couple new CDs for the occasion, happily blasting ourselves with the new Bob Dylan.Seven speakers, including subwoofer, is a whole lot of speakers for the cabin of a Jeep, and we think this is a good thing.Located under the sound system controls are big climate control knobs, with buttons for the new power windows above that.(Power windows in a Jeep!)

Between the seats are the shift lever and short four-wheel-drive lever, two cupholders and emergency brake, and a console that's wide and deep, if not long.The locking glove box is about one-third larger than before, and there's a convenient grab handle above it.This is a Jeep, after all, so the grab handle will be used in the bouncy bits.

Our Sahara had the modular Freedom Top, and we tried out all its positions on a gorgeous drive all around Lake Tahoe on a cloudless day, and then for a couple days in San Francisco.The vinyl pieces above each passenger easily lift off after twisting a fastener, and a larger section over the rear seat can also be removed although not stored in the vehicle.

The only problem was that we couldn't store anything else behind the rear seat, with the two roof panels there.Actually, we couldn't get four carry-on-sized bags behind the rear seat, even without the panels.And watch out for the rear glass; it rises on its own, and will whack you on the chin (or forehead, or nose) if you forget to step back.

The wheelbase has been increased by 2 inches and the track by 3.4 inches; the chassis has been stiffened and the suspension redesigned.All these things yield significant improvements in the ride and handling, but still, on city streets, the Wrangler is pretty bouncy, and out on the freeway it can feel squiggly over pavement changes.The driver needs to pay attention to keep the Wrangler going in a straight line.

That said, we drove the Wrangler at speeds up to 85 miles per hour on the open freeway, and it was stable and surprisingly quiet, when the pavement was smooth.When it was even slightly rough, we had to move into the smoother passing lane to find comfort.

However, it's important to note that our Sahara had the 18-inch wheels with Bridgestone Dueler on/off-road tires and high-pressure gas-charged shock absorbers.Standard on the Sahara are 17-inch Goodyear Wrangler SRA on/off-road tires with those shocks.The Wrangler X uses 16-inch Goodyear Wrangler STs, also on/off-road, but the shocks are low-pressure, so that combination might offer the best ride, with the standard Sahara setup somewhere in between the two.

The new 3.8-liter V6 that comes standard on all Wranglers is an overhead valve engine.It replaces the old 2.4-liter DOHC four and venerable 4.0-liter overhead-valve inline-6.It makes 198 horsepower (vs.190 hp in the previous six-cylinder) and 232 pound-feet of torque at 4000 rpm.The old six-cylinder made 235 pound-feet at a lower 3200 rpm, and this 800 rpm difference is felt, at least with the four-speed automatic transmission in our test Sahara.

Acceleration is good, but on those long uphill 75-mph grades between Lake Tahoe and San Francisco, the Jeep kept kicking down out of overdrive, fourth gear, until we turned the overdrive off (our Sahara was equipped with the Trailer Tow Group option).More torque at lower rpm might have prevented this.We didn't have the opportunity to test the standard six-speed manual transmission, but we're inclined to suggest it might be more compatible with the Jeep than this four-speed automatic.

The Wrangler Unlimited would have been a different animal on this road.The ride is significantly smoother and the handling more stable, thanks to a wheelbase that's 20.6 inches longer; but it weighs 315 pounds more, so the engine will work a bit harder.However, all the 4x4 Wranglers are EPA-rated at 16 city and 19 highway miles per gallon.

When we drove the Unlimited around Lake Tahoe, there were a lot of other Jeeps on the road, and our four-door never failed to turn heads.At the view points, fellow Jeepsters came over to ogle and marvel.Every one of them said they wanted to go home and trade in their two-door on the new four-door Jeep.

We were also behind the wheel of an Unlimited with the six-speed manual transmission on the rugged Rubicon Trail, where its capability was downright dazzling; in low range and first gear on the most challenging sections, we drove without using our feet: merely steering over daunting obstacles, and letting the vehicle do the rest.It's safe to say that the two-door Wrangler would be fairly astonishing.

The only limitation with the Unlimited was its turning radius of 41.2 feet versus 34.9 feet with the two-door.Six feet is a big difference.In San Francisco, we used the two-door's tight turning radius to make a U-turn in the middle of a street to snatch a parking space on the other side, like all good San Franciscans.

NewCarTestDrive.com correspondent Sam Moses drove Wrangler models up the Rubicon Trail, through San Francisco and around Lake Tahoe while preparing this report.