Brake booster issue?
 

I have had a couple of cases where the brake pedal feels stiff when starting the engine. Is that normal or could there be a vacuum leak? This is a new x535d with only 800 miles on it.

I have normally noted a stiffer, less travel brake pedal just before starting a vehicle and for a second or so thereafter. I'll check my X35d this am. Do you notice the difference just before and after starting the engine?

I have the same issue. Rock solid pedal with no travel.(Its stiff at the top, not the bottom) Have to really push the pedal every now and then to get it to register that I'm braking so the engine will turn over. Once its running, no problems. I thought it was just a normal deal as it comes and goes. I'll be interested in what others have to say on this.

Mine (2010 X5 35d) has a stiff pedal right before starting the engine but go back to normal as soon as the engine starts.

Chenhuan

i think its related to the electric handbrake...

My Audi does exactly the same

Good to know this issue is normal.

I believe this is a normal occurance. I happens on most modern cars and I always just thought of it as no power to the power brakes until the engine starts...

Both times before starting. After engine starts everything is fine. I did the old vacuum test by pumping the pedal before starting until completely stiff (by the way it holds a pretty good vacuum.) then starting the car, driving for a bit, then shutting it off. After ten minutes testing the pedal while engine is still off. Everything checks out. Just those two instances. May be the car does this for a specific reason under certain conditions as others have suggested.