• Oct 20th 2008 at 11:17AM
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Click for a high res gallery of the new ML320 Bluetec

Those of you planning to buy the new Bluetec diesel SUVs from Mercedes Benz will want to make sure you don't miss your regular service intervals or ignore warning lights. If you do, you might find yourself stranded at the mall. In order to meet new NOx emissions standards these vehicles and others from Volkswagen/Audi (not including the Jetta) and BMW use a urea injection system to eliminate almost all the NOx. The urea is stored in liquid form a tank on board the vehicle and slowly injected into the exhaust stream where it forms ammonia that reacts with the NOx and converts it to water and nitrogen. The tank is sized so that the vehicle should be able to go close to 15,000 miles without replenishment. The 7-gallon tank will be topped up at the regular 10,000 mile service interval. However, as with fuel, urea consumption is in part a function of driving conditions. If a service is missed or extra urea is consumed, a warning light and counter will appear in the gauge cluster. When the urea level gets critically low, the counter will give you 20 re-starts, after that the car will not start until at least two gallons of urea are added to the tank. Mercedes will be selling spill proof bottles of urea at dealerships that drivers can use to top up their tank, however this will automatically be part of the regular service along with oil and filter changes. Mercedes roadside assistance will also be able to top up the urea tank for stranded motorists. The urea solution, or AdBlue as it's called, will initially cost about the same as diesel fuel or about $4 a gallon, so filling at the 10,000 mile interval should cost less than $30. Check out our first drive impression of the Mercedes BlueTec diesels here.

[Source: Automotive News - Sub. req'd]

Photos Copyright ©2008 Sam Abuelsamid / Weblogs, Inc.

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    • 1 Second Ago
      • 6 Years Ago
      I can think of a free source of (slightly impure) urea that is ideal for the desperate motorist :-)
        • 6 Years Ago
        ,,the car will not start until at least two gallons of urea are added to the tank''

        You have to drink lots of water to accomplish this!
      • 6 Years Ago
      Urea or water...? We'll see how foolproof the system is. Since "AdBlue" is a solution that consists of 50% or 66% water I assume that just the level of urea is checked. So it should suffice to fill up with two gallons of water and then take the next possibility to fill up with AdBlue before someone recognizes...
      • 6 Years Ago
      Wait a minute... at $4 a gallon, it takes $30 to refill the tank? So the urea tank is almost 8 gallons? That's the same size as a Smart car's gas tank!
        • 6 Years Ago
        Depends on the vehicle. I think the tank in the GL-Class is 8gal. the others I believe are smaller.
      • 6 Years Ago
      If you think ahead, you can fill up that bottle slowly.. then use it when needed :)
        • 6 Years Ago
        I can see the option of having tubes run right into the passenger compartment. Kill two birds with one stone.
      • 4 Years Ago
      This is a great article for sure. I have bookmarked the site so that I can keep track of your progress in the future. Thanks and keep up the great work.
      • 6 Years Ago
      Even though the system is a foolproof,the increase in fuel price and consumption will definitely lead to this urea system it seems.In future due to heavy price and also shortage in gas and petrol we will be compelled to think about the "Urea system".

      • 6 Years Ago
      Couldn't you just bypass the sensor?

      It seems like such a deal breaker to give up a spare wheel for an additive tank.