Mercedes-Benz really wants you to know how green its new line of diesel vehicles can be. To that end, the German automaker calls them Blue and capitalizes EFFICIENCY. Subtle, no? In an effort to earn the badge, MB has tweaked its largest and most luxurious model with a 3.0-liter diesel engine, a seven-speed automatic tranny that decouples itself at stops, a power steering pump that only operates when necessary and low rolling resistance tires. Those are pretty simple changes, no complex electric motors here. Fuel mileage, though, is rather good for such a large vehicle, coming in at nearly 31 U.S. miles per gallon. In contrast, the marque's upcoming S400 BlueHYBRID only manages about 29 miles per gallon. If this sounds to you like it makes a resounding case for diesel vehicles, you're right. It does. Unfortunately, MB only mentions German pricing for the S 320 in the press release after the jump, not indicating whether the big blue sedan will be sold on our shores anytime soon or not.

[Source: Mercedes-Benz]