Considering a 4.8i or 35d E70

[shorty04]

Hi all

My wife and I are owners of a 2004 530i. We have two dogs and a baby on the way and are considering an X5 to replace the 5 series.

I had my heart set on a 2008/2009 X5 4.8i because of the performance delivered by the V8. However, after reading some issues (ie: valley pan leaks) I felt the risk of having to foot a $3-4k unexpectedly on the car was a bit out of my comfort zone. I've owned BMW's all my life and always have a good contingency fund set aside, but it seems that the V8 may be incredibly expensive to maintain.

I've also seen a few 2009 X5 35d with low miles that fall in our price range, and offer a bit more in savings with the fuel efficiency of the vehicle. I guess the down side to the 35d is that from what I am seeing, many of them do not come equipped with adaptive drive and some of the bells and whistles more commonly seen on the 4.8i.

I guess my main question is - how unreliable is the 4.8i? Does the valley pan leak happen inevitably to all V8's, and is there an approximate mileage that these problems start to appear? What I am hoping to find out is when shopping for a used 4.8i with 100,000km (60,000miles), will I have to sink a bunch of money to replace the cooling system right away, or is it something that should be done closer to 100,000 miles?

Right now I am leaning more towards the 35d. Even though they are 3-4k more expensive than the 4.8i, they do offer better fuel economy and the torque from the diesel makes it still sporty and enjoyable. That's primarily why I am not considering a 3.0 at this time.

Any help or guidance would be much appreciated