I drove the GL320 and found it a great drive with alot of interior room at a price in Canada, comparable to a BMW 4.8. Of course the 4.8 has much better performance, but the GL had much more usable space.

The problem with the GL (and ML) is the turbo lag. I wouldn't really call it a "dog", but if you aren't patient, you won't like it. Once it moves off the line it is fine, but it takes a second to build boost (from a stop), something the X35 won't suffer from. The GL320 was very quiet; almost as quiet as a gas engine and while underway, you wouldn't know you were driving a diesel. Some "first drive" reviews of the 335d comment that the diesel is a bit noisy. I guess I'll have to wait and hear the diesel in the X5.

At the risk of being flamed; to me a SAV (SUV, whatever) is about utility. I know there is a segment of the market that wants both, hence the previous 4.8is and the Posche Cayenne. But no matter how fast these vehicles get, they don't really handle like sports cars so I tend to assess a suitable SAV based on drive, performance and utility, not the fastest straight line performance.

Having said the above, I did find the GL's lag irritating and think it would bother me more as time goes on. I like the utility, but think the 35d would be the better daily driver. If the engine is quiet and I don't have to pay to much of a premium over the 3.0si, it may be the best compromise for someone who needs utility but also wants an engaging drive.

I'll reserve judgement until after the test drive.