On a BMW E46 330Ci, is it necessary to pull the handbrake lever when you're in 'P' mode?

Question

My flatmate drives a 2001 BMW E46 330Ci automatic transmission. I sat next to him while he drove us to the supermarket. When we arrived, I noticed that he only put the gear lever into 'P' and switch off the engine. I reminded him that he has not pull up his handbrake lever yet and he says there is no need to. I did not ask him why because I don't want to sound like someone who has not sat in a BMW before.

Is it necessary to pull the handbrake lever when you're in 'P' mode especially for BMW cars?

Answer 1

So, definitely not a stupid question. As was stated in the previous answer, this does not apply to BMW's alone, but to automobiles in general.

In a vehicle equipped with an automatic transmission, it is not really needed to apply the parking brake. The parking pin within the transmission will keep your vehicle in place without issue. Even on slight inclines, this poses no problems. If however, you are on a steeper grade (steep enough for the vehicle to noticeably move after putting it in park and taking your foot off the brake ... but apply the brake before you take your foot off the brake pedal), you need to apply the parking brake. This serves two purposes. First, as stated, to ensure the vehicle does not roll away if the parking pin should fail. Secondly, so you can get the car back out of park when it's time to go again.

In a vehicle with a standard transmission, it is imperative that you use the parking brake to secure the vehicle. Some people would believe that having the transmission in gear is good enough. Even with the engine off, the weight of a vehicle is enough to turn the engine over if it is in gear. Mind you, with the ignition off, the engine will not run, but it can still move. Secondly, unlike an automatic, when you leave the car in gear with the engine off, you are still putting pressure on the transmission. It's not good to have the static weight of the vehicle on the gears/bearing of the transmission. This can cause premature wear inside of the transmission. Again, you obviously wouldn't have any strain on the transmission when the auto is parked on flat ground, but then someone can still easily move your car. Drive a roll back recovery vehicle in front of it, hook up a winch cable to it, draw it up onto the flatbed, and drive away. No more car.

Answer 2

This is not BMW specific, but rather automatic car specific. Yes, it is always a good idea to use the handbrake, especially when parking on hills. This is because when you put an automatic transmission in park, the only thing really keeping the vehicle from rolling is the parking pin. Over time, or with enough force in an instance, this could eventually break. However, a lot of people no longer bother because of the idea that it is no longer necessary or lack of training.

Best case scenario is to try and avoid significant stresses to the parking pin. Come to a stop, keep foot on the brake, move into park, and apply the handbrake. Now admittedly on flat ground as long as the vehicle has come to a complete stop before moving into park, it probably won't matter a lot. But always better to be safe than sorry, and it really doesn't take that much time to apply/release, especially on modern electronic ones.