MSA, or motor stop-start, yields a 2-percent fuel efficiency benefit on the European Commission CO2 cycle, though there's zero change or advantage on the U.S. Environmental Protection Agency fuel economy schedule. While X3 buyers may see a gain in real-world fuel economy, it comes at the cost of noise/vibration/harshness. The engine restarts at every stop, engaging the system with the distinctive sound and feel of the starter turning.
This might not be much of a problem had BMW not done such a good job on the new X3's body structure and overall NVH, making start-up noise and feel that much more noticeable. Compared with anything else, especially the old X3, this is one tight, quiet, luxury compact crossover. Front seat or back, there's very little road/tire, engine or wind noise, making it probably the quietest model in its class.
While the rear seat doesn't recline or slide back and forth, it's a pretty comfortable place, with good legroom and very good headroom for near 6-footers. The rear door aperture is somewhat tight for entry and exit, probably a result of the stout body. Interior quality-the fit and finish and the richness of materials-now is up to the level of 3 Series cars, though only in matching the status quo in this segment. It comes with contrast stitching on the seats and dash, but the leather seat inserts aren't nearly as supple as what you'll find in an X5 or 5 Series.
BMW offered up a moderately easy off-road drive of the twin-turbocharged xDrive 35i at a farm outside Atlanta. The X3 was as quiet as could be on the mostly gravel, red clay road, and nicely demonstrated its long suspension travel over a few severe bumps. It proved you'll be comfortable driving the X3 to your remote second home in the woods, and you probably won't need the hill descent control at all, unless you need to roll down steep hills at 5 mph.