The BMW 335d clean diesel sedan arrives in showrooms this month, followed by the BMW X5 clean diesel SUV in January. Before the public has had a chance to decide on the value equation of its first two luxury diesel vehicles in the $40,000 to $50,000 price range, BMW is now considering an even more expensive clean diesel 7-series sedan.

The European 730d is powered by a turbocharged six-cylinder diesel engine and yields 45 miles per gallon. Even with this impressive fuel efficiency, BMW is gambling on a much-improved economy, and the price of gasoline heading back up, by the time the diesel 7-series would arrive sometime in mid-2010.

The price would most likely be 10 to 15 percent higher than the non-diesel—pushing the sticker beyond $80,000.

There are other reasons for BMW to consider carrying the European 730d to American shores. A diesel with fuel economy in the mid-40s would help BMW meet more stringent fuel efficiency standards on the way. As a comparison, a conventional version of the new 7-series is expected to grant just 16 in the city and 24 on the highway.

BMW dealers from the US recently gave the new 7-series diesel a test drive in Munich. “They all told me they wanted it,” said Jim O’Donnell, president of BMW North America. “It wasn’t in our plans, but we’ll look at it.”

If the 730d makes it to the US, it will probably utilize a clean diesel system similar to the one found in the BMW 335d. The technology, known as BluePerformance, utilizes a fluid called AdBlue, which is injected into the exhaust system to reduce oxides of nitrogen. BluePerformance is very similar to the Bluetec system found in Mercedes Benz diesel vehicles.