Diesel is desirable in the Mercedes-Benz ML320

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by By TOM VOELK / Special to KING5.com

NWCN.com

Posted on March 12, 2009 at 12:15 PM

Updated Friday, Oct 23 at 3:06 PM

Video: Driving Northwest: The Mercedes-Benz ML-320

Americans like European stuff. Somehow things from across the Atlantic feel premium. Croissants. Heineken beer. Heidi Klum. Face it, they're more special than toast, Pabst Blue Ribbon and Brooke Shields, especially after those minivan commercials. Yet for all that perceived sophistication, Europeans overwhelmingly choose one thing Americans find loud, dirty, and noisy: Diesel engines, not Gerard Depardieu. They have their reasons. Diesel fuel is cheaper over there and the mileage is better. They're also hip to the reality that modern diesels are much better that we Yanks understand. Over half their cars sales are diesels these days.

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Mr. and Ms. America will be believers too if they have an open mind and some cash to spend. Mercedes is once again offering diesels in the good old U S of A, this time with a BlueTEC designation. It's now available in E, G, R and M Class vehicles. BlueTEC is a turbocharged 3.2-liter V6 diesel that makes 210 horsepower. Most buyers only look at horses when determining a vehicle's power. Don't forget about torque. Torque is something diesels have oodles. You love torque, but may not know it. The ML320 SUV I'm driving this week has 398 lb.-ft. of the good stuff. A sport-ute is just the kind of rig for this kind of powerplant.

Diesel 101

The Mercedes BlueTEC diesel is a very refined engine. Tuck one into an attractive piece of transportation like the M Class and your neighbors may never suspect what's under the hood should they not spot the BlueTEC badges. As stated before, diesels offer up improved fuel economy, up approximately 25 percent in the ML.  And there's no performance penalty because torque is that powerful grunt off the line that we Americans crave. That makes this Mercedes mighty satisfying when tooling around city streets. Lots of low end torque is also good for towing, in the ML320s case 7,200 pounds. 

So if diesels are so refined, why aren't these engines more popular? A few reasons. Some of us remember the diesels of the 70s that were not only smoky and loud but severely unreliable when made by GM. More recently, diesels have been kept away by tailpipe emissions. For years California and the states that have adapted their strict pollution control standards have banned diesel sales because of the higher particulates they produce. Mercedes, VW, and BMW now have diesels that can now be bought in all 50 states.

Clean up your act

Why so clean? For one thing diesel fuel itself has been reformulated to contain 97 percent less sulfur. In 2004, CDI technology or common-rail direct injection made diesels much stronger, quieter and cleaner. Taking it a step further, BlueTEC uses a liquid called AdBlue.  In the cargo hold there's an 8-gallon talk filled with the liquid. The exhaust gets spritzed with this urea solution, making things nice for Mother Earth. E Class sedans won't get the AdBlue system until next year's redesign and won't be 50-state compliant until then.

AdBlue is very similar to what children would euphemistically call No. 1. It gets refilled at the same service interval as the Mobile 1 synthetic engine oil, meaning every 10,000 miles or so. In addition, a particulate filter traps soot. Every so often the exhaust temperature is goosed to 1,100 degrees Fahrenheit to burn it off. Ignore the multiple and generous warnings of a low AdBlue tank and BlueTEC vehicles will not move until it's topped off. A check with my local MB service center finds AdBlue priced at 14 bucks a gallon.

Inherently, diesels produce less carbon monoxide and carbon dioxide than gasoline engines, because they normally operate unthrottled with lots of excess air. But diesels usually make more nitrogen oxides or NOx because of their high combustion pressure and temperatures. This may make your eyes glaze over but it creates something that makes them burn - smog. Using AdBlue, NOx is cut by around 80 percent. 

Power runs deep

Inside the car at idle there's no diesel clatter to be heard though there's a smidge when outside. There's no startup delay anymore either. Accelerate from a standstill and the Hand of God seems to push the ML along; such is the magic of torque. Mercedes-Benz claims a 0-60 time of 8 seconds. A smooth shifting 7-speed transmission keeps the engine in its optimal 2,000-3,000 RPM powerband.

Once at cruising speed there's less immediate power on tap, making passing on two-lane roads less confident. It takes an afternoon to adjust to the diesel engine dynamic. There are paddle shifters on the steering wheel but really, the tranny does the best job of keeping the ML in the proper gear all by itself. It takes time to get used to the unique stalk selector of the gear box but this is no way a deal breaker.

Long distance companion

Ride firmness is adjustable with the $1,600 Adaptive Damping System. After playing in Comfort and Sport modes I leave it in automatic, where it seems happiest. In this mode ML corners well considering it's a sport-ute. The M-Class lives up to the Mercedes expectation that it should be quiet and comfortable. Driving 400 miles in one day with a passenger who never knew we were in a diesel, we were fresh enough to test the 600 mile range (but didn't). The computer read 26 miles to the gallon. Official EPA numbers are 18/city/24 highway - very good considering this is a sizable ute.

AIRMATIC suspension gives the ML 320 an off-road advantage with extra ground clearance available with the push of a button. Another bonus?  It automatically levels the ML when you load it up. In easy off roading, the M-Class doesn't so much as hiccup. It can pull stumps all day long, though how many people are going to do that with a Mercedes? Of note - BlueTEC MLs don't have spare tires. The AdBlue tank claims its real estate. ML320 rides on run-flat rubber that can go 50 miles when punctured. Theoretically SUVs venture off into very remote places and a spare could prove mighty handy. Something to take into consideration if you're Ranger Rick.

Haven't we met before?

For 2009 M-Class gets a new bold grille and other subtle styling tweaks. Casual onlookers won't notice, they'll just view the classic shape as handsome. The cabin is familiar to last year's, using materials of high quality. Compared to the new Lexus RX design it's conservative but hey, so is Sarah Palin and even Democrats find her attractive. Seats, which are synthetic leather on this particular test vehicle, boarder on being hard though ultimately supportive. They're heated. So is the steering wheel if the Heating Package option is ordered. 

Upgrading the audio system is sound advice

Go for the premium harman/kardon Surround Sound system and there's HD and Sirius satellite radio to go with AM, FM and weather band tuner. Unless you're Bill Gates you probably own an iPod and Mercedes offers full integration, placing the Mercedes 3 pointed star on the display. By the way, that logo means something: Land, sea, and air, the places where MB engines originally saw service.

There are a few gripes. I've said it before and I'll say it again: The stalk mounted cruise control can be confused for turn signals, at least for the first three or four days of ownership. Programming the nav system with four arrow keys that surround a button is tedious. ML's update doesn't include the knob based interface found in newer MB vehicles. Keyless ignition is available but only available in a $6,600 option package. Ka-ching.

Accommodations for five

Three adults will be good in the rear seat but the bench doesn't adjust much. Each position has a contoured quality about it; foot room is average. Back passengers get heated chairs as part of the Heating Package mentioned earlier. They're welcome when heading back from the ski slopes. Both front and back rows get side torso airbags to supplement the full curtain protection. If the kids are lucky, their parents will order the dual screen entertainment system that allows for "The Red Balloon" on one screen and "Sponge Bob" on the other. Those up front can watch on the nav screen if the ML 320 is in park.

The back hatch gets electric assist. The cargo area is very well trimmed and gets a handy 115V house style power outlet as part of the upgraded audio system package. The trunk is roomy, swallowing 11 packs of warehouse sized bath tissue. That's a lot camping gear.

The price of clean living

The moderately optioned tester I'm briefly living with stickers for $58,000. Prices start around 49. Go with ML350 with its gas engine to slice $1,500 off the sticker. Prepare to do some serious number crunching if all you want is money savings. There's a $900 tax credit on the ML320 BlueTEC (which rises to $1,800 for the G Class diesel). Diesel fuel is more expensive, about 30 cents a gallon over premium, which most luxury cars require. On the plus side, fuel economy is up by 25 percent. Use bio-diesel and it can be argued that it's more earth friendly. Add price volatility and you can see why this isn't an easy equation. It's best to drive both engine and find which you prefer. Mercedes' ML 320 BlueTEC proves that diesels are a desirable choice for some. All those Europeans just might be on to something.

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