Currently, premium gasoline in Detroit (the Cruze Eco gets its high EPA number with premium) costs about $3.70/gal. Diesel costs about $3.80/gal.
The combined EPA FE of the Cruze Eco is 33mpg. If the diesel gets a combined number of 34 mpg (matching the VW Jetta), then the cost per mile for each vehicle (fuel only, not including urea) is $0.11/mile!
This means that break-even will never happen, mathematically, at current prices. Only if GM discounts the Cruze Diesel below the price of gasoline vehicle would it make economic sense.
So the potential buyer is left with a decision: is up to 280 ft-lb of torque at 2000RPM worth the hassle of stopping to get urea fluid every 10k miles, and the cost penalty of $4,000?
Also consider that the VW diesel Jetta has a 0-60 time of around 8.3s , while the Cruze Eco gets to 60mph in about 9s (Car and Driver numbers).
My prediction is that the Cruze Diesel will not sell in any significant numbers. A few diesel enthusiasts might choose it, but the average buyer will see the price and opt for the turbo gasoline car.