In a deal signed on Monday, between German car maker and U.S. police car maker, Carbon Motors ordered more than 240,000 units of BMW's 3.0-liter inline six-cylinder turbo diesel--the same engine used in the X5. In the X5, the diesel is rated at 265 hp and 425 lb-ft of torque.

As per the Carbon Motors website, a total of 19,000 law enforcement agencies in the U.S. combined operate over 425,000 vehicles. These vehicles average 8-14 miles a gallon and sometimes drive up to 90,000 miles a year, which leads to an estimate fuel consumption of 1.5 billion gallons of gasoline and emission of over 14 million tons of carbon dioxide a year. The E7 will use an aluminum space frame structure, which will be built to survive a 75-mph rear impact and designed to last for 250,000 miles.

BMW sold nearly 500,000 diesel-powered vehicles worldwide in 2009. BMW deals in two diesel models in the United States, the X5 sport utility and the 335d sedan.