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2007 Jeep Wrangler Rubicon - Ready-To-Run, Part I

Posted in Project Vehicles on June 11, 2007
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Photographers: DaimlerChrysler

Even with the dust of the TJ-versus-JK debate still settling on most of the Jeep Internet forums, we were itching to get our hands on a new long-term project, a two-door '07 Wrangler Rubicon. So we stole one from the local dealer and went straight into evaluation mode from Mile 1. Was it as much of a pig as people thought? Could we get the options we wanted? Will the Electronic Stability Program (ESP) system keep you from having fun off-road? Is it possible to build it without the computers going nuts? And if this new Wrangler is as ready to run as we say, what really needs to be changed anyway? Read on, and stay tuned for future issues where we'll answer these and many more questions about our new Ready-To-Run Jeep Wrangler.

When choosing the particulars of our Jeep, there was no question we wanted the six-speed manual tranny. We also wanted a two-door because everyone at the time was looking to build the much larger four-door Unlimited model-plus, we didn't really need the extra doors or space for people and equipment (we were more interested in capability). We opted for the Wrangler Rubicon mostly for the more durable axles, the 4.10 gears, the rear locker, and the electronic-disconnect sway bar. The front locker was kind of a bonus, but we're still a little unsure of the 4:1-geared Rock-Trac transfer case that's standard with all Rubicon Wranglers; it's a little low for some of the wheeling we do. Rumor is that '08 models will be available with a standard 2.73:1 NV241 transfer case, a rear locker, and possibly the electronic-disconnect sway bar; this would be a dream combo for much of what we do. If your wheeling trips consist of graded dirt roads, then the Rubicon is too much Jeep for you. But, if slow-speed trail cruising and rockclimbing is your thing, then the Rubicon is the best ready-to-run vehicle available today, hands down.

Now, if you are interested in 37-inch or larger tires, swapping engines, axles, trannies, and transfer cases, then the JK may not be for you-yet. You'd likely be giving up a well-designed factory suspension, ESP, and even decent factory traction control just to have the new body style. If this is your plan, you would be financially ahead by simply starting with a TJ-at least until the used JKs are a couple years old and a few dollars cheaper.

Having grown tired of poor visibility through the scratched plastic windows of several Jeep soft tops, we opted for the Freedom Top hardtop this time around; it's way worth the $1,585 entry fee. Unfortunately, we still got the soft top, too, because the only way to get the hardtop is to get the dual-top option. The soft top has found a place in the corner of our garage.

Inside our JK, we were fished into the power windows, door locks, and security system. Are power options for pansies? Maybe, but being able to unlock and lock the doors with a key fob alone makes it worth the $585 . The security system will also likely save you some coin on insurance. Just a note for you naysayers.

The plan was to option in the MyGIG CD player/navigation head unit for an additional $1,590. It sounds like a lot, but it's really a bargain when you consider what you get for the money. It includes a CD and DVD player, full touchscreen navigation, and a 20GB hard drive that can store approximately 1,600 songs (over 100 hours of music), among other features. Unfortunately, the MyGIG radio is said to be for late availability (perhaps as late as the '08 model year). So with that option out the window, we checked the box for the single CD player with an MP3 input. It's perfect for feeding in music from iPods and other MP3 players-unfortunately, the devices have no convenient place to rest. The free one-year Sirius satellite radio subscription is also a nice perk. We'll probably eventually upgrade to the MyGIG in our Jeep at a later date when it becomes available.

All in all, our flame-red '07 Wrangler Rubicon priced out at a reasonable $29,650, plus tax and license.

There's a lot of hearsay floating around about what the new Electronic Stability Program on the JK does or doesn't do. We've heard some random, unfounded complaints about it-even from people in the industry who should know better.

If there is any one option to hold out for on your new Wrangler, we'd say it's the MyGIG navigation system. It wasn't available when we stole our Jeep, but it's likely we'll add it later.

The truth of the matter is that nearly all of the complaints stem from a lack of understanding the system and how it operates. ESP enhances directional control and stability of the Jeep. It corrects for over- and understeering conditions using brake actuation and reduction of throttle to help the Jeep maintain a desired path. The best way to understand it is to actually read page 108 of the '07 JK owner's manual. After that, take the Jeep out wheeling and make yourself familiar with the settings, their operation, and how each setting affects the handling of your Jeep. In some cases, you'll have to trust that the ESP is trying to save your ass, even if you think you know what you're doing behind the wheel.

The system has three settings: On, Partial On, and Off. The settings that areavailable to the driver are dependent upon what position the transfer-case shifter is in. Two-wheel drive offers On and Partial On; High-range 4x4 offers On, Partial On, and Off below 40 mph; and Low-range only offers Off.

Driving off-road with the ESP On is kinda boring and uneventful-and in some cases, you won't want it on. That's why it has a switch. But on the road, the system makes you feel pretty safe. It intervenes before something sketchy like tire spin or sliding gets started. It might actually be a neat feature if put under lock and key to keep reckless teenagers and other inexperienced drivers on a leash when they are in your Jeep.

The Partial On setting turns just about anyone willing to hammer the throttle and point the Jeep in the right direction into a professional driver. You can feel the brakes applying at individual corners to keep you straight at speeds. The system is especially good at stabilizing the nasty habit of overcorrection. This is perhaps our favorite setting for smooth, twisty dirt roads. It lets you get loose, but not too loose.

To turn the ESP all the way off, you'll need to follow the instructions in the manual. This manual override is only possible in high-range four-wheel-drive. This is the ESP and transfer case setting we'd recommend for the Rubicon models in soft, loose terrain like deep mud and sand dunes where wheel speed is a must. Non-Rubicons can run in Low range, where the ESP is already off.

New 3.8L vs. Old 4.0L
We got our greasy little mitts on a proprietary dyno chart and a few tech bits for both Jeep engines side to side. Once the 3.8L gets past break-in mode (as mentioned elsewhere in this story), it's making more power and torque than the old 4.0L for a much longer rpm range. This makes the 3.8L a much more driveable engine when mated in front of the NSG 370 six-speed manual than the 4.0L; it's kinda like comparing the new 24-valve Dodge Cummins to the older 12-valve diesel. The 3.8L is a little more civilized.

4.0L I-6 3.8L V-6/td>
Physical size (crank flange to crank nose)
778.1 mm 544.4 mm (233.7 mm shorter = 9.2 in.)
Weight (with flexplate and oil)
419 lbs. 363 lbs. (56 lbs. lighter)
183 @ 4,600 rpm (new std.) 205 @ 5,000 rpm (new std.)
231 @ 2,700 rpm (new std.) {{{240}}} @ 4,000 rpm (new std.)

Mile 15
The manual six-speed shifter feels kinda rubbery. I often miss-shift because I'm not used to the pattern. I end up rowing from Third to Fifth and Fourth to Sixth. It sure does seem like I stall it a lot, too. The clutch is much lighter than on a TJ with an NV3550. It seems to wander, or maybe I'm just not used to the light-steering feel. The interior is extremely quiet. The JK literally stinks once it warms up. It smells like burnt car when I park. And you can smell it even from several vehicles back while on the road. It must be something burning on the exhaust.

Mile 45
Forward visibility is way better than the pervious-model Wrangler. I really like the adjustable seat height. Even though I'm just under 6 feet tall, I keep it on the lowest setting.

Mile 150
Gawd, this thing feels like it's way down on power compared to the 4.0L. It's really hard to get into the rear seats. The passenger side has the seatbelt in the way, but the seat folds up. The driver side doesn't fold up all the way, but the seatbelt is out of the way. Fortunately, the JK rear seat is much easier to fold up or completely remove than the previous-generation Wrangler's. If you plan on using the rear seat a lot, you might want to consider the four-door Unlimited model.

Mile 180
I'm beginning to think it doesn't have less power than the 4.0L. Instead, it seems like the electronic throttle won't open all that quickly when you mash the pedal. It feels like the engine is wheezing for air. Could it be the computer is working to preserve the drivetrain during the break-in period? I'm getting about 17 mpg.

Miles 200-300
The burnt-car smell has finally gone away. Jeep engineers say it's the manufacturing oil burning off of the exhaust. I think the mpg gauge is inaccurate. The real combined city and highway mileage is about 16 mpg. I'm gonna test it.

Mile 320
I had a chance to get into an '07 four-door Wrangler Unlimited with 6,000 miles on it. It's quicker than my lighter two-door JK and it gets better gas mileage! What the hell is going on here?

Miles 650-1,000
Aha! The 3.8L V-6 feels like it's beginning to come to life! The throttle response is slowly becoming much crisper, and the Jeep is noticeably quicker. Jeep engineers confirmed that the computer is learning our driving habits and that it would take 650-850 miles before the engine operates normally. What a bummer that all of the 3.8L JKs that are testdriven at the dealer will be pigs until they actually break in. The mpg gauge is overly generous by about 2 mpg. Actual combined city and highway mileage is 16.5, and the gauge reads 18.2 mpg. I've pretty much gotten use to the shift pattern and don't stall the engine anymore, either. I'm still not a fan of the rubbery-feeling shifter, especially over bumpy dirt roads. It shakes around erratically.

Mile 800
Controllable off-road compression braking (without using the brakes) while driving steep downhill at slow speeds is only achieved in First gear Low-range. Any other gear or transfer-case range will just allow the 3.8L to rev-out, and the Jeep will build speed.

Mile 3,000
First oil change. Might be nice to have a larger filter. The oil spills out onto the axlehousing when removing the filter, but it's much less messy and easier to reach than the filter on the TJ 4.0L, which spills pretty much everywhere. Why can't these things be mounted vertically?

Mile 4,180
The JK has averaged 16.5 mpg since Day 1; the best tank was 18.4 mpg, and the worst was 14.6 mpg. Driving less than 70 mph and keeping the engine around 2,750 rpm seems to net the best mileage results.

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