Finally, a truck that sounds like a truck. Even if it isn't really a truck.

Close enough.

The Mercedes Benz GL is the only full-size SUV that is actually a crossover vehicle, built with the unibody structure of a car, but given the tall stance and overall look of a truck. The design gives it the same ride and comfort advantages that make smaller crossovers so popular, while maintaining many of the workhorse qualities desired by buyers who use their vehicles for more than just driving the kids to ballet.

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Real truck guys, the ones who will settle for nothing less than a vehicle built with a frame separate from its body, will tell you the GL is nothing more than some fancy-pants trying to look tough, like John Kerry hunting during the 2004 presidential campaign.

How many times have you seen him with a shotgun and camouflage jacket since then?

Mercedes is hoping for a little more street cred than that, and GLs can tow up to 7,500 pounds, putting them in the same league as full-size SUVs like the Chevy Tahoe and Ford Expedition. You can even order them with the kind of four-wheel drive system favored by serious off-roaders, with locking differentials and a two-speed transfer case.

To sweeten the deal, Mercedes even promises that if you buy one, it’ll cut your taxes and save you money at the pump.

Enter the GL320 BlueTEC, with a turbocharged V-6 engine under the hood that runs on clean diesel. The main reason for offering the model is fuel economy, and the GL320 scores big on that point. With an EPA rating of 18 mpg city/24 highway it gets 33 percent better mileage than the gasoline-powered GL450 and is the equal of the Chevrolet Tahoe Hybrid, which is listed at 20 mpg across the board.

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Those are serious numbers for a 2.5-ton vehicle with the aerodynamics of a Labrador retriever. The engine is also strong, with tons of torque. Its 398-pound-feet give the GL320 a nice kick off the line and even more impressive pulling power.

There isn’t an overabundance of horsepower, just 215, but top speed is limited to 130 mph anyway, so is that really a problem for you? A 7-speed automatic transmission makes the most of the power that is on tap and helps maximize fuel economy.

But what about all the smoke, and that nasty diesel odor following you everywhere you go?

It's been a while since we've seen much of that coming from passenger vehicles, but as of 2008 diesels have to meet the same emissions standards as gasoline-powered cars. Combined with the ultra-low sulfur diesel fuel that has also become mandatory, you'll never know the difference by sight or smell.

Mercedes-Benz pulls off this feat with the help of a little pollution potion called AdBlue, hence the BlueTEC name. AdBlue is a urea solution that is injected into the exhaust stream and helps break down the nitrogen-oxide molecules into their constituent parts, cutting levels of the smog-producing compound by up to 80 percent. Particulate traps and traditional catalytic converters take care of the rest of the bad stuff before it makes its way out of the tailpipe.

The 8.5-gallon tank of AdBlue under the luggage compartment will last for 10,000 miles and a refill is included in the GL320’s scheduled maintenance. Prices on AdBlue haven’t been set, but in Europe it costs about $3 a gallon, so a fill up should run less than $30.

There's no hiding the fact that the compression-ignition cycle that diesels run on just sounds different than a gasoline engine with spark plugs, but the click-clack clatter is well isolated in the GL320 and the motor is as slick as whatever it is that Mitt Romney uses on his hair.

Over the course of seven days, I got 20 mpg in mixed driving that was heavy on the city and sitting-in-traffic side. My speed for the week averaged out to 25 mph, but on the few open highway stretches I saw, 24 mpg was the norm.

Click here to watch FOX Car Report try to drive a Mercedes-Benz E320 Diesel 700 miles on one tank of fuel.

Unfortunately, I also saw diesel that cost about 60 cents more per gallon than gasoline. A year ago, when Mercedes Benz was putting the finishing touches on this meister-miser, the two fuels cost roughly the same, and diesel was looking good as an alternative to rising gasoline prices. Now, things are less clear.

No one can quite pin down why the price differential is so wide, but a combination of the added costs of producing the new ultra-low sulfur stuff and good old supply and demand are most likely to blame. That said, the gap is down from 74 cents at the peak of the market in July, so if you work at a hedge fund, the ball is in your court.

Even at the higher price, you'll still save money over a gasoline-powered GL thanks to the higher fuel efficiency. If they equalize, you'll be raking in the savings at the rate of more than $1,000 a year.

One thing Mercedes-Benz can guarantee is that you'll be at least $1,800 richer if you buy the GL320, because the IRS will take that much off of your next tax bill in the form of a New Energy Tax Credit, just like hybrids get.

The GL was introduced in 2007 and, other than the addition of the diesel model, not much has changed for 2008, so let me be brief in summing up the rest of the vehicle.

The day I took delivery of it, I had just given back a Lamborghini Gallardo LP560-4 that I'd been driving on a race track, and was on day 5 of being bombarded with Women's Olympic volleyball coverage on TV. What do you think I sat up in bed thinking about that night?

All I wanted to do was go and take the GL320 out for a spin, and SUVs are the last thing I'll get behind the wheel of when given the choice. The seats are just so comfortable, the thick leather covering the interior so warm and coddling, everything about it pieced together perfectly.

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You get so much for your money from a GL320 (estimated base price: $55,000), it’s hard to believe Mercedes-Benz makes can make any profit on it considering that the much smaller E320 sedan sells for nearly the same amount. Clearly, the decision to build GLs in Alabama, instead of Germany, has its advantages on the bottom line.

An optional Airmatic suspension uses air bladders instead of springs which can adjust the stiffness, giving the GL320 ride quality that is sublime for a vehicle this size. Neither bouncy nor harsh, it drives a lot like the E-Class. There’s just a touch of body roll to remind you that you are not in a sports car, but plenty of control beyond that point if you wish that you were. It’s no Porsche Cayenne or BMW X5, but it doesn’t seem to care.

Off road, you can raise the GL320 2.5 inches, and use Downhill Speed Regulation (DSR) to crawl down steep slopes while the vehicle regulates the brakes and throttle to keep the vehicle traveling at a set speed. If you’ve ever been frustrated that your cruise control doesn’t work below 25 mph, this system is for you.

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Finding your way around out in the wilderness shouldn’t be a problem with the navigation system, which can track your progress off marked roads, and store the route to help you find your way home. It also has goodies like live-traffic, which I found to be very accurate on a trip on Interstate 95 through Connecticut. Unfortunately, the system doesn’t automatically divert you around the tie-ups, but will offer several detours if you ask it nicely.

A touch screen would make entering destination names a little easier than using the directional buttons to scroll through the alphabet one letter at a time, but a telephone-style keypad lets you enter information text-message style and speeds things up for those who are savvy with this modern method of communication, I assume.

The sound quality of the Harman Kardon stereo is stellar and helped by a hushed interior. It would be nice if the CD changer was in the dash, rather than the glove compartment, but at least it’s not in the trunk. An iPod connector and TV screens for the rear seats are also available.

With someone over 6-feet tall up front, the person enjoying a film in the second row may find themselves with scuffed knees, though. Legroom there is good but not club level good. As far as cheap seats go, the ones in the third row are roomy and, if no one wants to sit in them, can be folded down electrically.

Mercedes-Benz kicked off the year with a mock “Vote for BlueTEC” rally at the New York Auto show, complete with balloons and sign-yielding party faithful. Primary season is now over.

The GL320 BlueTEC is scheduled to hit showrooms in October. Thanks to a broad platform that promotes energy independence while looking out for my personal interest in staying as comfortable as possible at all times, it gets my endorsement.

Then again, I'm not registered.

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2009 MERCEDES-BENZ GL320 BLUETEC

Estimated Base Price: $55,000

Type: Front-engine, all-wheel-drive, 7-passenger SUV

Engine: 3.2-liter turbocharged V-6 diesel

Power: 215 horsepower, 398 pound-foot torque

Transmission: 7-speed automatic

MPG: 18 city/24 hwy

What do you think of the GL320 BlueTEC?

Send your comments to foxcarreport@foxnews.com