Outside of Volkswagen dealerships, the stock of new diesel offerings in the marketplace appears to be growing. As it promised, Jaguar has just released two of its first-ever diesel cars for the U.S., the compact 2017 XE and this midsize 2017 XF.

The XF 20d shares the Jaguar-designed “Ingenium” 2.0-liter turbodiesel inline-four with the XE (and, still-to-come, the F-Pace SUV) that churns out 180 horsepower and 318 pound-feet of torque. But just as we were befuddled by the XE’s four- and six-cylinder gasoline engines delivering identical fuel economy estimates, we’re similarly puzzled over near-matching EPA numbers for the XE and XF diesels. The XF 20d gets EPA ratings of 31 mpg in the city and 42 mpg on the highway (1 mpg lower in the city versus the XE 20d) and 30/40 with all-wheel drive (exactly the same as the XE). While both cars share an 8-speed automatic, we’d have expected some greater distance between the two considering the XE is considerably smaller and lighter. However, the XF’s mid-tier status in the Jaguar lineup is reflected by a significantly higher price. At $48,445, the diesel is now the cheapest XF, at $4450 less than the previous base 2016 model with the 3.0-liter supercharged V-6. Unlike the diesel XE, which carries a $1500 premium over its gasoline siblings, Jaguar discounts the diesel XF across all 2017 trim levels ($3040 below the base 35t and $2350 below the Premium, Prestige, and R-Sport).

2017 Jaguar XE EPA F...