40 mpg dollars and sense: Chevrolet Cruze Eco saves fuel--as long as you shift yourself

Chevrolet has been getting some great mileage out of its ads about the Cruze Eco's fuel economy. "Cruze Eco offers 42 mpg on the highway by sacrificing nothing," says Chevrolet's website. But those claims come with a lot of small print.

What they don't tell you is that to get that 42 mpg on the highway, you have to opt for the manual transmission. Or that the regular Cruze 1LT with the same 134-hp, 1.4-liter turbocharged engine is rated at 36 mpg highway. Or that a Cruze Eco with an automatic will return an EPA-rated 26 mpg city, 37 mpg highway, and add $900 to the price compared with either a manual-transmission equipped Cruze Eco or a Cruze 1LT with an automatic.

So is the Cruze Eco worth it? We took a look at the numbers for a Cruze Eco with each transmission and compared them with a Cruze 1LT. Since the Cruze Eco requires the Connectivity Plus Cruise package, we added that to all three models.

The Cruze Eco includes low-rolling resistance tires, a rear spoiler, front grille shutters that close on the highway for better aerodynamics, and a slightly lower ride height. It gets an EPA-rated 28 mpg city, 42 mpg highway with the manual transmission, compared to 24 mpg city, 36 mpg highway for the Cruze 1LT.

But the more real-world comparison is to use the overall combined EPA mpg rating, because drivers don't spend all their time on the highway. The Cruze Eco has a 33 mpg overall rating, while the 1LT is rated at 28 mpg. Both cars use the same engine.

Assuming you drive the national average of 12,000 miles a year and pay $4 a gallon for gas, the Cruze Eco with a manual transmission will save you $260 a year on fuel compared with a Cruze 1LT. The only sacrifice is automatic gear shifting.

If you prefer an automatic, however, you'll only save $114 per year on fuel. That means it will take eight years to recoup the extra $900 cost of the Cruze Eco automatic vs the Cruze 1LT with the standard automatic transmission. (GM says that the Eco accounts for about 5 percent of all Cruzes sold.)

GM says the 2012 Cruze turbo with the automatic will see a 2-mpg increase for highway mileage, rising to 38 mpg, while the Eco model with the automatic bumps up to 39 mpg. Pricing has not been announced. (Read: "Chevrolet promises to increase 2012 Cruze fuel economy.")

This scenario just reinforces the need for consumers to look beyond ad hyperbole and do their research before buying a car. Make sure you compare apples to apples, and decide if maximum mpg is more important than some conveniences like an automatic transmission.

Related:
40 mpg dollars and sense: Honda Civic HF may save fuel, but doesn't really save money
Are the Ford Focus, Fiesta SFE models worth the money?
Is 40 mpg the new 30? Reading between the ad lines

—Eric Evarts