There are pictures of all of these vehicles available on the internet but it is very difficult to compare size and shapes when you see them separately. I took my 9-4X to a few car dealers and snapped some pictures with other crossovers.
This is not a price and technical comparison which I will try to do at a later time. It's only how they physically compare to the Saab 9-4X base/premium model.
The crossovers/SUVs in this thread are the Mercedes GLK, M and GL, BMW X3 and X5, Audi Q5, Volkswagen Touareg, Volvo XC90 and Cadillac SRX.
This picture shows the Mercedes GLK in the middle and Mercedes M on the right. The GLK is much smaller and the 9-4X is almost the same size as the 2011 M-class.
Here is the GL-class, Mercedes' full-size vehicle. It is obvious larger than the 9-4X and it starts at US$62,570 so it is in a different class.
Next to the GLK class which is a small crossover. I would classify the 9-4X as mid-size.
Next to another M-Class. Similar physical size but different luxury and price class.
The 2012 M-class seems quite a bit larger than the outgoing 2011 model. It also is quite a bit larger than the 9-4X. Starting price for the 2012 M is $49K so the two can not be directly compared.
The 9-4X pictured next to its Swedish mate, the Volvo XC90. It appears to be a little bit larger. I wish they had an XC60 on the lot which is a better comparison in size and price to the 9-4X. I always liked the styling of the XC90 but it starting to look quite dated. And a bit frumpy as well.
The 2012 Volkswagen Touareg is quite a good looking vehicle. It appears to be about the same size but it looks a bit larger with the higher hood and belt line. Trade-off with this is a smaller windshield and I really like the outward visibility of the Saab 9-4.
The Cadillac SRX is actually quite a good looking vehicle. Not everyone may like the style but it is not offense. There are too many different lines and creases for my taste but still a good design. If you didn't know the SRX and 9-4X are based on the same platform and roll off the same assembly line, it would be very difficult to see their relationship.
The 2012 Audi Q5 is a very nice looking crossover and appears to be almost the same size as the 9-4X. However, it does look a bit more premium and the 9-4X can't quite match that.
The BMW X5 is quite a bit larger but, like the Mercedes M-Class, it also is in a different class.
I found this BMW X3 parked at a beach parking lot. The X3 is quite a bit smaller. While design and taste are always open for discussion, I think the X3 has quite a few awkward lines and design. It makes me think of an angry and unhappy bulldog while the 9-4X has more of a happy and confident look. The hatch of the X3 is very square and I am not sure what they were going after with the taillight design.