I've read that BMW still makes gasoline powered X5s; I just don't understand why

Seriously, The 35d engine is nearly perfect for our use of an X5: mostly 2 lane country roads, in fairly hilly terrain, with the need to tow serious loads (2+ tons including trailer) fairly frequently. This is where the 35d is at it's best. On the open road at legal speeds (or maybe just above) w/ 2 people and a cargo bay full of groceries, building supplies, etc. with or without a trailer in tow. In this world, the 35d has the performance of the V8 w/ better mpg than the gasoline I6. OTOH the 35d is not a very good fit for primarily short trips, in town, empty (e.g. commuting less than 5 mi.). The diesel just doesn't get good mpg until fully warmed up.

We've had our 35d since last August w/ just over 11,000 trouble free* miles. Despite the DEF angst you'll read about in this and other forums, we have had NO DEF issues - no warnings, no top-up needed, no hassle at the dealer to get it filled right - nothing. The maintenance on the 35d is only slightly more complicated than the 35i because of the DEF. And even this is really only an issue when the 35d is regularly stored at temps below freezing**.

Funf Dreisig

* Our X5 was one of the ones that was built with the early batch of faulty turbo air temp sensors. Because of what I knew about the air temp sensor issue from reading this forum, it was replaced under warranty one morning while my wife drank the dealer's lattes in their massage chair.

** IMO the freezing DEF in the passive tank issue grew way out of proportion last winter, due to owner and dealer inexperience with the DEF system. A $6 bottle of DEF stored above freezing can be used to top up the active tank with about the same level of skill/effort required to top up the windshield washer fluid.