let your X5 really warm up

[JCL]

You will always get accelerated wear upon cold startup. The choice you have is whether you make that cold running interval longer by idling it, or as short as possible by driving it moderately. Putting load on the engine warms it more quickly. Stretching it out just results in increased wear.

Start it up, and as soon as you have oil pressure (less than 10 seconds) start to drive it moderately. This presumes you can see out the windows, ie not waiting for the defroster. No high RPM operation during this warm up, and no lugging it. Driving it causes it to warm up more quickly than idling, though, thus reducing engine wear.

Nothing different here about a BMW or any other modern vehicle. Drive them as soon as it is safe to do so.