I have had my Z4 E89 since September 2020 with a dealer service history that I am sort of questioning, looking through the book in detail it appears that engine oils have been change at the correct intervals but other tick boxes in the book have not been ticked as much as I would have liked. Anyway after reading different articles on this forum I decided to give it an in between service myself, this has left me wondering why its so costly as the hardest part was getting the car on axel stand high enough and safe, take that time out and it took me approximately one and a half hours to do the following. Engine oil\filter change, Gearbox oil change, Air Filter, Cabin Filter, took plugs out cleaned checked and refitted, checked brake pads disks and all bushes etc that I could I then plugged in my Snap-on Diagnostics had no faults job done. I would bet the gearbox oil had never been changed as I could not believe how much better the gearbox felt after. Oh Yeah and no special tools needed. If you can prove these jobs have been completed with receipts and maybe pictures its got to be better than a dealer stamp for an oil change???????