I took my 09 G550 out for some pretty serious off-roading about a month ago and figured I'd give my impressions. It came with 22" wheels and 305 Z-rated tires on it from the dealer, which I didn't want, but they offered me a great deal so I bought it. For reference, I have a fully built '77 Ford F-150 short box that is my normal off-road machine (33" off-road tires, front/rear 10k lb interchangeable winch, 3000 lb helper winch, 4 ton come-along, 150 ft of chains and straps, high lift jack, 2 spare off-road wheels/tires, extra oil/coolant/gas, full tool kit, you get the idea). So yes I know a fairly low profile 22" z-rated tire is terrible for off-road, but when in the dry, rocky terrain in the mountains, they actually do just fine. I did cut the sidewall on one after 50 miles of trails and only a mile from the highway. I replaced them with all-season Pirellis for now until I get some custom 17" bead-locks next year with serious tires.

I figured I'd see what happens with the tires before I got rid of them for a new set. I took a buddy that had never done more than fire roads (which he called off-roading) and I think he crapped his pants a half dozen times. I took it down a trail that drops 1000+ feet into a river canyon and back up, and I would rate it as expert in difficulty. It's mostly gravel, with lots of large rocks, extremely steep grades, and bare rock sections.

The Review:
Power
The good: Everything. That low-end TQ is awesome. In Low range is was almost too much.
The bad: Nothing to say, it has everything you need.

Suspension
The good: Wheel travel is huge. It soaks up bumps without any trouble. Each wheel can articulate a huge amount so you always have traction. I even made it up a 30+ degree slope when at the bottom, I only had the front left and back right wheels on the ground. The car was slowly rocking back and forth putting the front right then the rear left wheel about 2 feet up in the air deciding whether to flip or not. Luckily, a little patience and a judicious use of power at the right moment set it back on 4 wheels. (I wish I had a picture!)
The bad: Having done this same trail a bunch of times in my pretty high up Ford, which never felt like it was going to tip, I almost rolled the G twice. The center of gravity and stability weren't as good as I expected.

Drivetrain/Diffs
The good: The front diff cover is mounted on the front of the diff, as it should be in any serious off-roader not running skid plates. That came in handy once when I got the front diff up on a rock and both front wheels off the ground (I took a crazy line). It was covered in rock dust/chips when I got off and took a look at it, but it was barely even scratched. I ran with the center diff locked and that was all I needed to go right over everything. The traction you get is amazing too. I almost never slipped even when I forgot to lock the center diff after stopping at the bottom of the trail, and I still made it up a 30 degree gravel slope with almost zero slippage.
The bad: Only being able to lock the diffs when rolling at 5 mph or less is not a good feature. You've gotta lock them before you get stuck. Also, they unlock when you stop the car. If you don't remember to lock them when you start up again, you can get in trouble. I almost did but the traction was ok until I could get to a spot to do it. Another problem is that you need a level or downhill area with a couple hundred feet of distance for them to lock. That can be hard to find on a difficult trail.

Body / Exterior
The good: It looks like it belongs off-road.
The bad: I managed to scrape the back right corner of the bumper when I was in some crazy position where it hit a rock or the ground. I still don't understand the angle I was at to do it (Again I wish I had a picture!). A bit better approach/departure angle would help. I also threw up a rock on a fire road that went forward of the car and bounced up into a fog light and shattered it. I think they're mounted too low.

 

How does it compare to a Range Rover(not the Sport), Im just curious as they seem direct rivals. Ive argued with friends the good and bad of both. But we've never driven new RR's or a Gwagon.

 

damn, after that great description i was hoping for at least a few pics of being out on the trail!

 

Having a built off-road truck, despite the drawbacks I mentioned, what a stock vehicle with Z-rated tires could do off-road was impressive. I did a lot of research on the Range Rover and Porsche options (I have a 911 Turbo, my 2nd 911, so I'm a dedicated Porsche guy), and the G-wagen came out on top in every category. The ball joints are the size of large grapefruit, which I've never seen on anything short of a dumptruck. The front diff cover being reverse mounted only exists on one other car in production today, the H2. That was a requirement of the AM General engineers who had final say on all components of the H2. The G-wagen is built to do some very serious off-roading and I'd put it against anything in production and I bet it would come out on top.

Here's a few pics of a spot I stopped at. Kind of tame, but they're pics!

 

nice! glad to see one being used the right way, instead of by some trophy wife to goto the mall.

 

As a former owner, I can say without question, the G is one of the most amazing vehicles on the road. I can't wait to purchase another one.
I only wish I could enjoy it off road like you do....looks like a great time

 

Yeah, I bet everybody that sees the 22" wheels thinks it never sees the dirt. I bought it mostly because of the off-road capabilities. The only thing that bothers me is that you can't get a trailer hitch for it any more because of safety regulations (fuel tank protection/skid plate). I've bought 2 other options, one that is a retrofit to make it like OEM, and another that bolts to the skid plate. I just want to tow a 1000 lb driftboat/trailer combo so I may just go with the skid plate one for now. The other one requires cutting the plate and welding a bracket to the frame. Yeah, I know bolting a trailer hitch to the skid plate isn't a great idea, but for such a light trailer, it'll be fine. The plate it pretty darn robust.

Colorado has so many places to go off-road and the G is just awesome. I've never driven in anything that can take a fire road so fast and comfortably!