When it comes to bringing a diesel engine to the United States, Mazda has talked the talk for a long while but has yet to walk the walk. Years ago, the company discussed bringing a Mazda 6 diesel to our shores, but when that fell through, the popular CX-5 crossover became the prime candidate for Mazda’s 2.2-liter Skyactiv-D engine in the States. Mazda confirmed last year that a CX-5 diesel is happening, and we caught a prototype version of such a vehicle running around Michigan this weekend, suggesting that its official arrival may not be too far off. The CX-5 we spotted was devoid of any badging, but certain clues identified it as a diesel-powered model. Look closely and you’ll see an intercooler mounted behind the lower front grille, a tachometer that appears to redline at a low 5500 rpm, and a single exhaust pipe instead of the standard gasoline-powered CX-5’s dual outlets.

Mazda has stated previously that the diesel engine will be offered on the 2017 CX-5 and that it will arrive in the second half of this year. At this point, however, Mazda has yet to share any more information about the CX-5 diesel, which brings that timing into question. A Mazda spokesperson told us that the company is currently working with the EPA and the California Air Resources Board (CARB) toward final emissions certification on this powertrain but wouldn’t share any more timing details. Mazda noted to us that preproduction models may be running around; this prototype has a Bosch sticker on its windshield, which could indicate the supplier—known for its fleet of diesel test vehicles in our area, southeastern Michigan—could be conducting testing for Mazda.

If and when the CX-5 diesel arrives, it’ll have some competition in the form of the 2018 Chevrolet Equinox, which offers a 1.6-liter diesel engine that achieves up to a 39-mpg EPA highway rating. We’ll keep our ears open for more news on Mazda’s oil-burning crossover over the next few months to see if the company can make good on its earlier promises.