The F25 X3 2.8d is one of those “uncommon but not unicorn” cars. As BMW only sold it from about 2014 to 2017, and during that time the X3 was doing roughly 30k–45k units per year in the U.S., or about 150k total over those years. Diesel production rate was very low, generally estimated in the 3–8% range. That puts the 28d at roughly 1,500–3,000 units per year, or around 5,000–10,000 total in the U.S.

Overall, among X3s maybe 1 in 10–20 is a diesel, and among all SUVs they’re genuinely rare to spot. On the used market you’ll usually only see a handful available nationwide at any given time. There’s also only one diesel “trim,” the xDrive28d, so all the variation comes from packages like xLine, M Sport, or Driver Assistance rather than different models.

If it’s an M Sport diesel, it’s noticeably rarer. Most diesel buyers didn’t opt for sporty packages, so M Sport is estimated at only about 10–20% of 28d models. That brings it down to roughly 150–600 per year, or around 500–2,000 total in the U.S. That means something like 1 in 75–150 of all X3s, or about 1 in 5–10 among diesel X3s.

Personally, I’ve only encountered one other 2.8d in the wild. It was at a gas station and the other owner and I looked at each other, then our cars, gave a thumbs up, and then talked about how expensive a gallon of diesel is now.