We've known for a while that Bentley is planning a diesel variant of the Bentayga, but it wasn't clear from where the engine was being sourced. According to Telegraaf in Holland, Bentley is pulling the diesel from the heart of its sibling Audi, and it won't be an effort to improve fuel efficiency. The all engine features two exhaust-driven turbos plus a 48-volt compressor that effectively cuts lag to nothing and propels the SQ7 TDI to 62 mph in 4.8 seconds. Expect a similar number in the Bentley.
This engine is exactly what the Bentayga needs. There is nothing wrong with the W12 in the standard model, and you could argue a 12-cylinder engine is a better fit in a Bentley. But that's just because W12 sounds better than diesel. While the gasoline engine may more powerful and therefore make the vehicle quicker (leading to that "fastest SUV" claim Bentley loves), no owner will actually be racing their Bentayga to its theoretical top speed of 187 mph. They will be racing away from stoplights, though, in an effort to leave more plebeian cars and SUVs behind. All that low-end grunt is what those owners really want.
It's unclear if Bentley will bring the Bentayga diesel to the United States, and given the current state of diesel here, the proposition seems unlikely. Expect an official debut at the Paris motor show in October.