Quote:
Originally Posted by newtoav
First post here... I've got an X5d on order and was interested in the topic.
One thing that no one has mentioned is altitude. It's been my experience that at high altitudes turbo lag is much more noticeable. Since all engines lose power as the air gets less dense, could it be that the effective power output at the non-turbo charged phase is much lower to the turbo-charged phase (above 1500 rpm), making the lag more noticeable at higher elevations. I wonder if this could be the reason that some people report terrible performance, while others hardly notice it.
A different thought - some BMW transmissions have really non-aggressive settings, making the car almost always want to star in second gear, unless really pushed. Question for you guys suffering from lag - if you manually shift to first and then start, is the lag just as noticeable?
I am hoping that the experience isn't as bad as it sounds... really looking forward to the new ride, and to its performance.
Cheers,
JB
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I use my X5 in the Denver area at altitudes ranging from around 4900 to 5400 feet. The OP is in Colorado Springs which is a bit higher, I think in the 5800 to 6500 foot range. I don't experience much in the way of "turbo lag" and would not expect it to be much different at higher altitudes. In all of my other turbo cars (couple of Subarus, GMC turbodiesel pickup, 335i) the turbos fared far better than NA cars in that they made up for the altitude better.
One thing that I'm wondering about is if some folks may have different versions of the engine software. On my 335i there was a BMW update (29.something) that changed the way that the turbos behaved, to the point where the car felt quite "laggy" compared to the original programming. It took quite a few complaints by owners for BMW to respond with an update, but even after the update I never felt that the car had returned to its original responsiveness. There were various attempts at explanations for the change relating to reliability, but I think that they were just hoping to "patch" the cars to try to keep the HPFPs from failing. It may be interesting to check the software versions on the X5's (if possible) to see if there is any correlation.
The throttle response thing is also something to consider. I've heard about the reset sequence, but I've also heard that you just need to drive the car hard a bit and it will adapt. Mine has adapted quite nicely, and I leave it in "D" most of the time and it takes off quite nicely.
BTW, you can "launch" the X5 35d easily enough:
- Hold down the DSC button until everything is off
- Put the shifter in DS and push it forward to M1
- Push on the brake pedal
- Rev the engine to around 1700 RPM (torque peak)
- Release the brake pedal
- Hold onto your hat
It will shift at 4500 RPM or so, but you may do better to short-shift it a bit to keep it in the powerband. You probably don't want to do this often, but it will leap off the line like the proverbial scalded cat.