My '00 Golf TDI 5spd turbo'd and chipped was pretty consistent for 42mpg Summer and 39mpg Winter for the same commute and 9yrs/250,000 miles. But it was pretty used up by 350,000. I know cetane is an issue, but I really have now way of testing. I do buy 90% of my fuel from the same 3 stations and have for 10yrs. The Cruze was averaging 45-46mpg over the Summer and seems to be about 41-42mpg this Winter, all hand calculated. I will say it calculates out a bit better than the computer says I'm doing by about 3mpg. I did once see 53mpg over 50miles running 65mph on the interstate on a cool morning with no AC late this Summer.
I'm completely happy with the MPG, even with DEF thrown in.
My old Golf 1.9L with the upgrades and the Cruze 1.6L are very similar power wise. VW shifted smoother and the turbo came in much faster. However the Cruze is quieter, eeks out a little better MPG, and has 20yrs of improved conveniences.