This is one of the more comprehensive reviews so far. Here is an excerpt on some of the gas mileage results they recorded:
2014 Chevrolet Cruze Diesel First Drive – Review – Car and DriverOn the 292 miles south we just stayed with traffic, much of it at 70–80 mph, and our average with a few stops, including the Auburn Cord Duesenberg Museum in Auburn, Indiana, was an indicated 44.9 mpg. Heading back to Detroit on the freeway,...During the first 40-mile stretch at a boring 55 mph, we saw a Prius-like 58.4 mpg, followed by another 30 miles at 65 mph for a still-impressive 53.9 mpg, and a more satisfying 20 miles at 75 mph and 43.4 mpg. A 30-mile off-freeways-through-towns stretch brought 43.1 mpg.
Also, I'd forgotten there is no spare with the car. But since i pay for On-Star now, it doesn't matter as much. I just push the button and someone will come and deal with the tire.