Point of order. If you have the Adaptive M Suspension options, your suspension is
always adaptive - varying and modulating the amount of dampening at each wheel / strut constantly.
Drive modes allow the drive to select different modes or themes or personalities (pick your descriptor) for your X3. Think of them as performance Targets. Sport / Comfort / Eco are the base values. Each adjusts the tuning of your steering, engine, throttle response, transmission etc. If you have the Adaptive M Suspension; then the dampening of the X3 is also adjustable. It to corresponds to a target mode.
In Comfort, for example, the ride is softer, but the Adaptive M Suspension is still in constant flux as road conditions change. It allows the suspension to instantly soften for a pot hole, then run firm again immediately afterwards.
I am going to make up numbers to illustrate the point. If a strut has a rating of 0-100 with 0 being very soft and 100 representing the firmest ride:
Comfort = target 40 (varies from 10 to 70)
Sport = target 70 (varies from 30 to 90)
Sport+ = target 80 (varies from 40 to 95)
Again, completely made up; but there will be a logic to the system that acts on an algorithm which would operate similarly.
Adaptive Drive mode is the mode with a floating target for steering, engine, throttle response, transmission and adjustable suspension. While in Adaptive Drive mode the computer watches current conditions and driver input along with recent history to determine on-the-fly which mode best represents your current driving style. It's a nice feature. With Adaptive Mode engaged, you're basically in Comfort, but will spool up to Sport if you goose the gas and start to drive in a spirited fashion. My only complaint is that it should be the default drive mode from the factory - if you have purchased the Adaptive M Suspension.
Personally; I think this is a must have option. I like it far better than the more expensive air suspension systems out there (which I find all to soft w/ too much roll). At only $700, it's the best bang for your buck of all the options. It allows you to really change your X3's personality in a fundamental way.
Heh.. I think I said most of this earlier.. but seems like some people skipped before. ;-)