That is an opinion.The tires that originally came with the diesel Cruze will yield you the best milage. You will lose milage with just about any other tire due to weight and tread compound. Matter of fact the OEM TPC rated FuelMax tires on our cars are different then the retail version. I can guarantee the tires are the cause of your lost milage.
I'm telling you. the Pirelli Cinturato Strada AS from Discount Tires are wonderful, ride better, are quieter, and are delivering slightly better mileage than the OEM Goodyears did. This is my second set of Pirellis. My first was on my Sonic 1.4T Hatch, and they really woke that car up in the corners. I believe these are the P7s, but numbered for Discount only.