How do you check your transmission fluid on a 2005 BMW 645CI?

To check the Transmission Fluid on a 2005 BMW 645Ci, start by warming up the engine to operating temperature and then shift through all the gears. Locate the transmission dipstick, which is typically found near the back of the engine bay; remove it and wipe it clean. Reinsert the dipstick fully, then remove it again to check the fluid level; it should be within the marked range. If it's low, add the appropriate transmission fluid through the dipstick tube, ensuring you use the correct type specified in your owner's manual.