Originally Posted by Lassaxi
I didn't say you wouldn't notice the extra torque in the 335, but it's a bigger deal in the heavier X5. The 335d is going to pull damn hard down low, but the 335i doesn't really have a problem with feeling sluggish off the line. The higher HP in the 335i is beneficial because that car is relatively light, and is better poised to take advantage of gearing.
The X5 is a much heavier vehicle, and needs more oomph to get moving off the line. An X5 3.0 feels somewhat sluggish, and needs a heavy foot to feel responsive. It's much more lively with the V8 engine (which has great HP and torque), but you pay a significant fuel economy penalty for the V8. The torquey diesel engine is going to make a heavy car like the X5 feel much more lively in everyday driving without incurring the same mileage penalty as the V8 gas engine.
The 335d will gain a similar benefit, but it's comparator, the 335i, is already fast, powerful, and reasonably efficient. The X5's comparators are either sluggish (in 6-cyl form) or inefficient (in V8 form), which means that the diesel engine will be a more compelling option in the X5 than in the 3er. I think Alpine6speed's exactly right- if you drove all four cars back to back (335i, 335d, X5 3.0si and X5 35d), you'd probably find the diesel to be a more compelling option in the X5 than the 3er.
Lassaxi--I have driven the 3.0 X5--and it is indeed not very exciting--I cannot imagine it loaded with passengers and cargo--so I agree with you that the diesel will really enliven that truck. And as far as mileage compared to the V8-the diesel will surely come out on top.
I am already in love with my 335i's low down pull and what I feel is a very creamy mid-range. I really do not miss the V-8's I came out of. What I am most enticed by is the idea of all that torque and the 7 speed DCT---I really wonder if the diesel will be that much heavier--does anyone know the weight?-since i do a lot of highway cruising the combo of strong-mid-range torque and the fuel savings are appealing to me. I am very interested in driving these cars back to back. (Of course I would love either powerplant in the E91 in a perfect world-but that;s just me.)