Chevy Cruze diesel: 46 highway mpg, but only 27 in town

• Big jump from Chevy forecast at Chicago auto show in February
• Cruze diesel trickles out May and June%2C widely available this fall

Chevrolet says the diesel version of its Cruze compact sedan will be rated by the government at 46 miles per gallon on the highway, the best of any non-hybrid car.

But mileage ratings in the city and in city/highway mix aren't so spectacular.

City rating: just 27 mpg; mix, 33 mpg.

While the highway number gives Chevy a win over chief rival Volkwsagen Jetta TDI diesel's 42 mpg highway rating, the Jetta TDI prevails in the other categories. It's rated 30 mpg in the city and 34 mpg in mixed driving.

VW is the only mainstream purveyor of diesel at the moment. The 2014 Cruze diesel goes on sale in some cities the next few weeks, then nationwide and in Canada by early this fall.

Mazda also joins the mainstream-brand diesel parade this summer with a diesel version of its redesigned, 2014 Mazda6 midsize sedan. It has given no details on that car.

Diesels are more expensive than gasoline cars, and diesel's usually pricier than gasoline. But diesel vehicles usually can go much further on a gallon.

Chevy had forecast 42 mpg on the highway when it unveiled the car at the Chicago auto show in February. Chevrolet says it was being conservative and that its engineers have been working on continuous incremental improvements to boost mileage.

Cruze diesel, which comes only with a six-speed automatic transmission, starts at $25,695, including $810 shipping. Jetta TDI with automatic is $24,885; manual starts at $23,795.

Chevy says the Cruze has more standard features than the Jetta, including leather seating, larger wheels and a longer powertrain warranty.

The Cruze diesel is rated 148 horsepower, 258 pounds-feet of torque. Jetta: 140 hp, 236 lbs.-ft.

Chevy notes that it sells Cruze worldwide and has sold more than 33,000 diesel-power models in other countries since the compact launched in 2010.