I came down a high speed road at 100 km/h when a car suddenly jumped out in front and I max braked. The 730d had insane brakes to the point it is crazy. This went well..... Somewhat worse brakes and outcome could be different.
BMW 7 series have shorter stopping distances and IMHO VW not putting safety as main priority.
You not gonna convince me, In my opinion drum brakes is legacy technology, but I accept you may have different opinion .....
I get what you mean, but anecdotes are pointless and you're still reacting to something I didn't say, because you're generalising the whole topic of brakes.
I could write a similar (true) anecdote that happened to me while driving a work van, and come to the conclusion that you don't need BMW brakes because I avoided an accident in an old Ford. But it would be pointless, right?
So instead, how about we discuss what I'm >>>not<<< saying, and maybe things will be clearer?
I am >>>not<<< suggesting that if I were to design a BMW 7 series, it would have drum brakes. I would put discs all over that car, the bigger the better, the more calipers the better.
When you design a car that weighs 2,5 t and is essentially built to sit at 250 km/h on the Autobahn all day, obviously you need high performing brakes.
But more importantly; you're designing a car where you can be pretty sure the brakes will actually be used. The car is heavy and if the customer didn't want to drive fast occasionally, chances are they'd buy something else cheaper to buy and maintain and with much less depreciation.
So one of the prerequisites for choosing disc brakes is fulfilled; the brakes (also on the rear) will actually see use from time to time.
It's the right choice >>>for that application<<<.
I'm also not saying that drum brakes are in any way "always superior" to disc brakes. But it seems to me that you think I'm saying that, and that you're generalising similarly by suggesting disc brakes are always better, such as for heavy autobahn cruisers or F1 cars.
But this is about the ID.4, an electric car with a top speed of what, 160 km/h (and obviously it will likely not spend much time at those speeds due to the range dropping fast).
The car has regenerative braking and a rear wheel drive unit. In other words, while the rear brakes on any car are applied much less than the fronts, and this car will only be applying the rear brakes once it is at max regen, once the front brakes are applied and they are applied hard enough that the rear brakes begin to actuate.
This will happen very rarely under normal use.
So this car doesn't really fulfill the prerequisites of disc brakes that they must occasionally be used to maintain their surface condition.
It's the right, the reliable and thus the safe choice to put drum brakes on the rear of these cars, simply because odds are when you do actually need the brakes on this car, the rear brakes - if they were disc brakes - would either be covered in rust/corrosion or in a particle "grime" that in both cases reduces the efficiency of the brakes severely, to the point of cancelling out any advantage they might have had from being disc brakes in the first place.
It's essentially the same reason trailers use drum brakes; they sit still a lot of the time and they're rarely driven like a hooligan. So when the brakes are needed, they would be covered in rust or grime and not really work, if they were discs. For this reason, trailers use drum brakes and for the same reason, they are the right choice - and even if stopping a 3,5 t trailer can be a tough job, they get it done.
This doesn't mean I own shares in drum brake companies like Continental, nor that I advocate then generally. It doesn't mean I intend to suggest they are superior to disc brakes in general, and it surely doesn't mean that I would suggest Mercedes to use drum brakes in their next S class.
It simply means that I feel it is very incorrect to label VWs decision as a safety concern when it is in fact not. It's the appropriate choice >>>for that application<<< and the measured numbers back that up.
Its absolutely fair that someone would not want that based on preference, but in my opinion it's not fair to call it a safety concern at all.
