Yup this is so true... i just took home my first x5 last night and it was a good thing i saw a youtube video of adjusting the tailgate height prior to delivery.
I too have a standard garage door height and i was so worried about hitting it that i had to back up the car and took a measuring tape to make sure it cleared. I started 3 notches down, but it was too low and a dangerous head knocker at the edges (hard to miss especially at night). i ended up adjusting it one notch down, but my finger was next to the button just in case it didn't clear
