I am on X5 #7 and on my second 35d (2011 and now 2017).
Besides my 4.8is and 4.8i...the diesels are hands down my FAV X5s, if not fav BMWs.
The power/torque of this engine is the best pairing for the size and weight of the X5. Also, the mpg is amazing. I almost always get 25-30 mpg in the city (gentle driving, but not "old lady"). On the freeway, with that sweet spot of 65-70mph, my mpg will always be above 30mpg! On a full tank of diesel, I will travel at least 550 miles, but I have seen over 650 miles too! Impressive for a vehicle of this size and weight!
X5 35d has a pre-heater for cold weather driving. You will get almost instant cabin heat. Although, for us here in So. Cal...very cold is 28-32F, the HVAC starts providing warm cabin air almost right away. Of course heated seats and my heated steering wheel are nice too!
35d has NO, ZERO, Nada diesel smell, black smoke! In fact, I traded my 2017 X5 xDrive 40e plug in electric for my current 2017 35d, and the driver rear tailpipe was always black on the 40e. Same as with my 2011 35d & now my '17 35d...tailpipes are always clean. I mean, insanely clean. Nothing!
Sound! I honestly wish I had more diesel sound (I like it). The only time I really hear that I am driving a diesel, is when I am in a parking structure or underground garage. My 2011 35d sounded WAY more diesel than my current '17 35d.
BMW says 2018 diesels are coming, but they are scarce (if not here yet). Also, MBZ and Audi has no 2018 diesels. RUN, don't walk, to get a 2017 35d! Best of the best!!
