At the 2008 Detroit Auto Show, Acura showed off a new 2.2-liter four-cylinder diesel engine and announced it would debut a production version in 2009. Informed speculation says that the oilburner would be equipped in the new TSX, a re-badged version of the European Honda Accord that currently offers the engine. Honda engineers have even presented documents outlining the new exhaust developed for the engine in the last two editions of the Society of Automotive Engineers World Congress.
Unfortunately, it looks like we might not get a chance to sample a diesel TSX in the U.S. after all. An anonymous poster on the MotorTrend forums is claiming that Honda has not been able to pass emissions certification with the automatic transmission TSX diesel. The manual transmission version is fine, but the poster claims there wouldn't be enough demand in the U.S. market for the manual-only model and Honda will therefore drop the diesel altogether. We don't know if this is true, and Acura has not yet responded to our request for a comment. It will most like be a "no comment" anyway.
For what it's worth, we're suitably dubious about the source and the information, particularly considering that modern cars with electronically controlled automatic transmissions typically perform better on emissions and fuel economy. This is primarily due to the engineer's ability to have more control over the interaction between the engine and the transmission, and less to do with the person behind the wheel. Hopefully the story is untrue, because it would be nice to finally get a Honda/Acura with some low end torque.