[Monterra]

We will see a 4cyl. diesel in the next 3 series- pretty sure that's been confirmed...Whether they choose to debut it in the X1 or wait for the new 3 to launch is the question I believe. From what they've said this 4 banger diesel will put up numbers akin to the N55. That seems an insane claim but even if its ~230hp and 300lb-ft (not a leap from the 23d right now) that will be awesome I think. Here's the quote:

With the upcoming change in CAFE fuel economy standards, BMW sees the addition of a four-cylinder diesel as key to meeting those strict rules. Although it will be a fuel miser, BMW says the 2.0-liter four-cylinder diesel engine it’s developing for this market will be tuned for performance.

“This engine needs to match the acoustic qualities of a six-cylinder, and it need to match the performance, as well as performing better in terms of fuel economy and emissions,” said Baloga. “Our four-cylinder diesel will be so good that people will readily accept it as a replacement for six-cylinders. The target is to produce enough horsepower to be comparable [in performance] to our N54/N55 [328i /335i engines] six-cylinder turbos.”

This means that BMW is aiming to get in excess of 300 hp and 300 lb-ft of torque from a small 2.0-liter diesel engine. For comparison, BMW’s 3.0-liter turbocharged diesel mill puts out 265 hp and 425 lb-ft of torque.

When the engine makes its way over here, it will initially be offered in the 3-series and X3. Baloga said there is a strong possibility of it appearing in the 5-series. If it’s accepted in the X3, it will migrate to the X5 as well.