BMW has good reason to have faith in its engineering. While Saab used to make much of having been "born from jets," BMW powered not only the first operational jet fighter, but a great number of awesome war machines before and since. Most of the time that kind of well-founded confidence pays off in the form of great cars and a good customer experience -- most of the time.
BMW wishes to officially inform you that its transmissions do not leak. BMW would like you to know that its transmissions do not use fluid, do not require fluid changes for the "lifetime of the car," and that you have no reason to mess around with its perfectly engineered gearboxes for any reason, ever. The engineers of Bayerische Motoren Werke AG are insulted that you'd think that their definition of "the lifetime of the car" is a completely arbitrary and meaningless term implying only that "Zee auto vill last as long as vee say it vill last."
Translation: The E46 chassis doesn't have a transmission fluid dipstick, because BMW says the fluid will never leak, will last "the lifetime of the car," and never needs to be checked. Should you ever disobey the Germans and decide to keep your car past its undefined "lifetime," you can change the fluid by flushing through the transmission cooler lines every 50,000 miles. If the car already has more than 100,000 miles on it, don't completely flush the old fluid out for new fluid, or you risk frying your transmission.
Now...stop messing mitten zee BMW gearbox, dumpkopf!
