Fresh off a complete second-generation redesign, the Mercedes-Benz GL350 BlueTEC is the oil-burning variant - and the entry-level model - in the automaker's GL-Class lineup. A luxury SUV with an efficient diesel engine screams "Roadtrip!" - so I loaded up my family of four and headed north up famed California State Route 1 to Hearst Castle for the day. The well-isolated GL proved every bit as spectacular as newspaper magnate William Randolph Hearst's "ranch" on the hill, seemingly determined to justify its recent accolade. The heart of the GL350 BlueTEC is a 3.0-liter four-valve direct-injected turbocharged diesel engine rated at 240 horsepower, but delivering a whopping 455 pound-feet from as low as 1,600 rpm. There is a bit of turbo lag off the line, especially when rushed, but the standard seven-speed automatic does an admirable job hustling the 5,467-pound vehicle to 60 mph in under eight seconds. In real-world driving conditions, the torque makes it feel quicker than that.

Fresh off a complete second-generation redesign, the Mercedes-Benz GL350 BlueTEC is the oil-burning variant - and the entry-level model - in the automaker's GL-Class lineup. A luxury SUV with an efficient diesel engine screams "Roadtrip!" - so I loaded up my family of four and headed north up famed California State Route 1 to Hearst Castle for the day. The well-isolated GL proved every bit as spectacular as newspaper magnate William Randolph Hearst's "ranch" on the hill, seemingly determined to justify its recent accolade. The heart of the GL350 BlueTEC is a 3.0-liter four-valve direct-injected turbocharged diesel engine rated at 240 horsepower, but delivering a whopping 455 pound-feet from as low as 1,600 rpm. There is a bit of turbo lag off the line, especially when rushed, but the standard seven-speed automatic does an admirable job hustling the 5,467-pound vehicle to 60 mph in under eight seconds. In real-world driving conditions, the torque makes it feel quicker than that.

Fuel economy was impressive for its size. The EPA rates the big BlueTEC at 19 mpg city, and 26 mpg highway. During our 407-mile road trip, we averaged 25.3 mpg (including city cycles at both ends of the excursion). With a 26.4 gallon fuel tank, highway range is in excess of 650 bladder-bursting miles. The GL350 BlueTEC can't claim outward visibility as its strength. We'd like to see larger exterior mirrors. Thankfully, a handful of useful (and very effective) electronic nannies and a 360-degree camera ease maneuvering. Despite its size, a tight 40.7-foot turning radius allows stress-free U-turns on most city streets. Excellent bi-xenon headlights, with Highbeam Assist and Active Curve Illumination take all fear out of night driving, too. Driver and passenger enjoy heated, cooled and massaging sport seats that are more comfortable than your mother's loving arms. Second row passengers are treated nearly as well, provided their own HVAC controls with multiple air vents.

The third row has always been a GL-Class strength, and it will easily accommodate full-size occupants without a murmur of protest. 2,800), but for this driver, it's a must-have option. The autonomous radar-based adaptive cruise control scans the road up to 600 feet ahead, allowing the GL350 to automatically follow, accelerate and decelerate with other traffic (it will even come to a complete stop). Better yet, it's bundled with Pre-Safe Brake, Active Lane Keep Assist and Active helping to prevent rear-end collisions. The geek in me really liked how it displayed the distance to the vehicle I was trailing in real time. My list of gripes was small, but worthy of a mention. First, the iPhone interface plug is too big to fit devices with protective cases. Second, the electronic parking brake isn't intuitive (push down to set, lift to release). Third, the round volume control button in the center console is too small for large fingers.

The twisting power of an ox gives the Mercedes a quick jump off the line and a confident pull on the highway, even when passing on a grade. Sport utility vehicles are perfect candidates for turbodiesel engines, and the GL-Class is no exception. As mentioned, the Feds slap the GL350 Bluetec with a combined fuel economy figure of 19 mpg. However, we saw 26 mpg during most of our highway cruising and our overall economy was in the low 20s the whole time. Most amazingly - and we are still shaking our heads in disbelief - the "lifetime economy" trip computer on our tester had never been reset, reading an even 22.0 mpg over the past 4,222 miles. An impressive feat for anything of this size and weight. The biggest Mercedes SUV is one fine land yacht, but the competition in this well-to-do segment is fierce. In addition to the Cadillac Escalade, the stage is crowded with the Lexus LX570, Range Rover, Infiniti QX56, Audi Q7 and Lincoln Navigator. The Escalade vaunts its hybrid powertrain, while the Q7 offers a diesel. The QX56 from Japan points to its technology, while the traditionalists, both the LX570 and Range Rover, take pride in their off-road prowess. The Navigator, meanwhile, boasts luxury appointments and an industry-leading infotainment system. Nevertheless, single category wins don't make champions among these captious rivals - front-runners need to deliver across the board.