I have just purchased a new 3.0 and I'm experiencing some lag right off the line. Maybe it's normal given that it's a heavy vehicle and the displacement is only 3.0 liter.
I've been renting and driving a Hyundai Sonata 4cyl model and it's very peppy on a stop light. And even my previous vehicle, which is a year 2000 minivan is pretty fast taking off.
But the X5 3.0 is pretty slow to go from a complete stop. After pressing on the throttle, I have to wait for about 2 to 3 seconds for the engine to come alive, pick up speed and be more responsive. It's not very sensitive to my throttle input, like sluggish off the line. It feels like I'm starting from a second gear, yeah, that's exactly what it feels like.
Is this what you 3.0 owners are experiencing too? It's not peppy or responsive or light on its feet. I know it's a heavy vehicle, but if it's slower than a Sonata 4cyl (which was very responsive to my throttle input from a complete stop), then I don't know...
It's a lot better after picking up some speed though.