The BMW Z4 is a series of cars with the unique feature that you can check the oil on the dashboard using their computer system. You never have to get your hands dirty like you do when you check the oil level the old-fashioned way. Using a computer to check the oil level is more accurate than trying to visually gauge the level on the dipstick.
Drive your Z4 for at least ten minutes to warm up the oil. You shouldn't read the oil level on a "cold" car, as it won't be accurate.
Put your Z4 into park on a level surface area, not a tilted driveway. Leave the engine running.
Press the "1" button on your turn signal stick until the dash reading says "Oil".
Press "2" on the turn signal to see the current oil level. It will show you a picture of a dipstick with the level on it. It will also tell you whether you need to add oil, and how much.
Your oil reading should be between the "Min" and "Max" levels on the display's graphic.