The BMW 4.4L V8 is smoother and more responsive than the Jeep's 4.7L V8. The fifty extra horsies come in handy in the heavier X5. Acceleration seems to be about 1 second better 0-60MPH. Gas mileage is identical. The sound insulation of the BMW cabin is much better than the Jeep's. However, I did notice a rumbling when at rest and idling. It sounded like a low frequency exhaust resonance, perhaps.