no it is not. 4runner is based on simplified Land Cruiser Prado/GX platform, not vice versa. V8 4Runner actually has similar powertrain to LC/GX but lesser 4Runners have actually different suspensions/4WD. They are more like Hilux/Tacoma's...

Every truck in Toyota range has been derived from Land Cruiser platform, although much simplified, hence driving feel is completly different as well.

GX is upscale version of Land Cruise Prado, known for its legendary reliability in adverse conditions.

It is better built and has better materials than RX.

All that being said, it really depends on what she needs from the car...

 

Regardless of which is based on which, the 4runner, GX, and Prado all share an almost identical body on frame chassis. I don't know about 4wd systems or suspension - they're similar enough unless you get into the optional stuff. The V8 motors and transmissions are identical.

They are, overall, a very well done rebadge job. Still genetically, 'fraternal twins', in most ways.

 

Best to go over the RX and GX forums for this question as there are real responses from those in the know.

But to add...same thing to you as I tell everyone else. It's your money, it's your car(truck). Why ask others? Go drive them both and buy what YOU want.
Now I can say that when the GX came out I thought it was HORRID! Damn that is ugly. But....now...look at my sig. I actually do really like this thing. I mean really like it. If you go with the GX, get the Kinetic suspension and it will corner flat and does not feel top heavy in the least bit though it APPEARS it does. Keep in mind that all SUV's are not going to handle like a sports car. But everyone believes they are the know all of everything cars, so go buy what you want. We have both in the family and both are very nice SUVs.

http://www.4wheeloffroad.com/roadtes...ar/winner.html

http://www.edmunds.com/insideline/do...4/pageId=61279

 

I think I responded to a similar question in one of the specific forums. I have both vehicles (albeit a RX330, not a 350), and my whole family prefers the GX.

In comparison terms:

Long trips: The GX, though less fuel efficient, provides a "magic carpet" ride. With more trunk space, and a more spacious-feeling cabin, it allows you to pack more stuff and feel less claustrophobic on those long journeys. The RX does offer a more car-like ride, but it is jostled more rigidly by road imperfections, whereas the GX has a much softer suspension feel. At higher speeds (75MPH+), the GX may feel a little too floaty from the backseat, but at all times the feel from the driver's (and passenger's) seat is smooth, controlled, and commanding (the RX doesn’t offer as much of a commanding position due to lower seating and less apparent torque). We've taken some long drives (twice from NJ to Key West, often from NJ to MA for college searches, and very often to the Jersey Shore (approx 150 mi, or 3 hrs)), and we always take the GX for these reasons.

Short Trips: Around town, the torque of the GX is a blast, and the presence of the vehicle is unparalleled. However, the RX achieves better mileage and is smaller to control. This comes down to personal preference when you take the test drive. You should be able to notice these differences on your test drive.

Interior: While the RX offers a modern interior and the GX has a more classical design (perhaps relatively outdated), the GX interior is of higher quality. Leather (in my particular case) is superior in the GX, and the fit and finish appears better also. We have a dash rattle in the RX but (knock on wood) no such issues with the GX. However, the additional off-road capabilities of the GX means an additional lever (the 4WD transfer case) and more buttons (DAC, Diff. Lock, 2nd Start), so the GX may be too much for some people. I must note, however, that these additional features are not annoying, they are just unnecessary to most people. In snow, though, it is fun to play with the features on the GX.

Exterior: Although personal preference will vary, the GX, with a more aggressive stance and design, provides a nice sense of strength, but some might say it looks tall and ungainly. The RX, on the other hand, is sleeker (more modern), but growingly ubiquitous. Both are pleasing to look at, so make your choice.

Our Verdict: Originally we were looking at the RX, and we weren’t even considering the GX because it cost more and was perhaps too large for my mom to drive. However, that V-8 engine under the massive hood demanded a test drive, and we realized that the GX actually drove smaller than it looked. With the smoother cloud-like ride (keep in mind it does drives like a truck though), more cargo space, and a relatively insignificant price difference based on our situation, we chose the GX. A year later, in need of another car, we ended up with the RX. We are very happy with both cars, but given the preference, I’d take a GX any day.

I hope that helps!

 

Here's an easy question you/your wife should ask:

Does the family need the extra 3rd row? If not, just get the RX for her. Cheaper, easier to drive, better mpg.

After the clunk fix and the suspension setting on 3/4, I can take 30-40 mph curve comfortably at 60+ mph, but not 95mph.

90 mph is reached easily, effortlessly, and confidently.

Looks are always subjective.

Me personally, I couldn't wait to get back into my gx when I have the rx as a loaner.