Around me diesel is about $4.25/gallon. 87 octane is $3.85/gallon, and 15 cents/gallon cheaper in the next town over while diesel is still $4.25/gallon. Assuming 15k miles a year, the numbers break down as follows: Assuming 30 mpg for the gas Cruze, fueling it for 15k miles would be $1925 per year. Assuming 40 mpg for the diesel Cruze, that same 15k miles would be $1593. So one would save $332 in fuel over the course of the year. For people who drive 50-60k miles a year, the savings of a diesel could be significant, and even more so if the spread between gas and diesel is less than around here.