We’ve been hearing for a while that Audi would soon populate its U.S. model range with optional diesel engines, but to date only the Audi A3 TDI and the Audi Q7 TDI come with oil-burning engines.

During yesterday’s early-morning Audi conference call, Audi of America president Scott Keogh clarified the brand’s position on a diesel A4. It’s in the pipeline, but it won’t arrive on these shores until after the launch of the new B9 platform A4 in 2014.

The reason why is easy to understand. The current B8 version of the A4 was launched in 2008, and despite a refresh for the 2013 model year, it’s rapidly approaching end-of-life.

Re-engineering a diesel A4 for the U.S. market, according to Keogh, would be an expensive and time-consuming process, which makes little financial sense if the car has only a few years of life remaining in its current form.

Though it’s not yet clear when in 2014 the new MLB Evo-platformed A4 will hit these shores, we’d expect to see a 2.0-liter TDI version debut in Audi showrooms at the same time as gasoline-powered models.

The new oil-burning A4 won’t be alone, either. Audi has plans to introduce TDI versions of the A8 sedan (which should hit dealers in the second quarter of 2014), followed by the Q5 crossover, the A6 sedan and the A7 sedan.

Given the growing population of diesel options soon to be available from a variety of manufacturers, will 2014 be remembered as the year that diesel went mainstream? We certainly hope the answer is yes.