In 2008, Mercedes-Benz plans to sell three diesel-powered vehicles that use a controversial urea-injection system to control emissions.
Mercedes says the three vehicles -- the M, R and GL-class SUVs -- will meet 2010 emissions standards requiring diesel engines to run as cleanly as gasoline engines.
The key to launching the vehicles in all 50 states is the urea-injection system, also known as selective catalytic reduction. SCR reduces oxides of nitrogen, the smog precursor known as NOx, by injecting urea periodically into the exhaust system.
But if the ammonia-based acid runs out, the vehicle no longer will meet emissions standards.
That has EPA regulators worried because they don't like systems that depend on drivers' maintenance. The agency plans to release guidelines for urea in the coming weeks.
The EPA rules will spell out such things as how automakers must warn drivers when the fluid is running low, how long the vehicle can be allowed to run without urea and drivers' ability to buy and refill urea throughout the country.
In Stuttgart, Mercedes-Benz spokeswoman Edith Meissner said the automaker sees no unsolvable problems with the warning system or urea availability.
"There are negotiations with suppliers and the EPA. We expect they will be finished in the next month," Meissner said. "The good news is that it seems we will find a solution. The question is which solution is the preferred one. But there is no hurdle, no obstacle."
Because of strict emissions rules, Mercedes diesels have been shut out of California since 1999. New York, Connecticut, Vermont, Massachusetts and Maine also have adopted California's emissions standards. Mercedes is especially eager to re-enter California and New York with its diesels, not only because those states are two of the largest but because Mercedes diesels traditionally have sold well there.
Meissner said the urea warning system would include a text message that tells drivers how many miles they can drive before the fluid runs out. She also said Mercedes is working on a distribution system for urea that is independent of dealership service departments.
"The idea is: If you can sell Coca-Cola and windshield-washer fluid at filling stations, you can also sell urea in small amounts, such as half a gallon or one gallon," she said.
Mercedes wants drivers to have the urea tank filled at the dealership at each scheduled oil change. But Meissner said the company also is working to set up a hot line for drivers to call so they can get urea sent to them overnight if the tank should run out in an area of the country where there is none available.