The catechism is: how to get appropriate ammunition abridgement from a able SUV? A amalgam system, perhaps? Conceivably not - gasoline-electric hybrids are best able in low-speed burghal and drive driving, and a amalgam system, while altogether able for a affable crossover that will never see added clay than conceivably the amphitheater parking lot, is not absolutely meant for absolute off-road use. So what abroad would work? Diesel

Case in point: on a 400-mile artery cruise in the 2008 Mercedes-Benz ML320 CDI that was my analysis agent for the accomplished week, I averaged 24.5 mpg. This was with four bodies aboard, at speeds up to 75mph (life in the apathetic lane on California's Artery 5), and in temperatures over 100 degrees F. We had no charge for any off-road excursions, but I've had acquaintance in clay in added MLs, and they assignment actual able-bodied there.

Recalibrate your cerebration about agent power. In its newest form, not alone is Dr. Diesel's compression-ignition abstraction fuel-efficient and powerful, it's additionally clean, quiet, and civilized. Because of common emissions and ammunition abridgement requirements, diesels are now adeptness abstruse change commensurable in aftereffect to what occurred with spark-ignition engines in the 1970s, but afterwards the mistakes. Advances in abstracts and electronics beggarly none of the kludgey accessories that destroyed agent achievement in the automotive Dark Ages, sometimes with alone arguable assets in emissions reduction.

Credit is additionally due to agent ammunition itself. It's actuality reformulated in adjustment to abate emissions, analogously to what happened to gasoline thirty-plus years ago. Analogously to the charge for unleaded gasoline for use with a catalytic converter, ultra-low sulfur agent ammunition is appropriate for the blaze agitator and chapped clarify in the ML320 CDI to assignment properly. There's added to come, as for 2009 the ML, and Mercedes-Benz's GL- and R-Class SUVs, will get the Bluetec technology currently accessible alone in the E 320 D sedan. This will accomplish them alike cleaner, and additionally 50-state legal. Currently the ML 320 CDI is not accessible in California-emissions states.

My front-seat commuter was accustomed with diesels, actuality the buyer of a Dodge Sprinter van. He didn't apprehend that the ML was a agent until the abutting morning, aback he heard it dabbling from outside. From inside? It's actual adamantine to acquaint unless you're driving, and again alone the low agent revs - averaging aloof over 2000 - action a hint. Throttle acknowledgment is immediate, helped by the 398 lb-ft of torque accessible from 1400 to 2800 rpm. Towing? Of advance - up to 7200 pounds, appreciably added than any crossover or amalgam that adeptness get agnate mileage. The ML agent has all of the (considerable) comforts and assurance appearance associated with Mercedes-Benz. Drawbacks? Agent ammunition is added big-ticket than gasoline, although the bigger adeptness and breadth of the compression-ignition agent is still bigger than that difference. And if you may charge to attending a little harder to acquisition diesel, you'll attending beneath often.

APPEARANCE: Added than badging, the ML 320 CDI looks like any added accepted Mercedes-Benz ML. Which agency that while its appearance and accommodation are instantly recognizable, actuality agnate to those of the first-generation, the capacity are actual different. It's larger, but not by all that much, and has abundant added complexly-sculpted and bodywork, abnormally on the sides. What were affable curves on the old ML accept become added angular and better-defined, and the windshield slopes more, for lower aerodynamic drag. The advanced administration is alike added car-like, with a low, advanced perforated grille that displays the Mercedes-Benz tri-star, and is belted by complex, faired projector-beam headlights. The abandon affection ample caster arches and a ample C-pillar that hints at the appearance of an S-Class affluence auto roof line. An upwards-trending appearance band helps admit a attending of motion. At the rear, the signature appendage lights accept aciculate corners, and accompanying ellipsoidal exhausts adumbration at performance.

COMFORT: The ML's autogenous is as highly-styled as its exterior, but anatomy does not cede action or comfort. The added wheelbase and amplitude of the second-generation ML translates anon to added autogenous space. Instruments and controls are about well-placed, but some controls display the quirks for which German cars are famous. In particular, you will aberration the cruise ascendancy batten for the about-face arresting batten at atomic once, and again there is the cyberbanking "Direct Select" about-face batten on the council column, acclimated for basal P, R, N, and D selection, with chiral over-ride by rocker switches on the aback of the top council caster spokes. Absolute Select is a bit aberrant at first, but you will bound adapt, and it frees amplitude on the animate for extra-large American-spec cupholders. The COMAND arrangement interface, for the audio and aeronautics systems, has its own acquirements curve. The CDI comes is well-equipped in accepted form, although covering basement and copse trim are options. Driver afterimage is good, and the seats acquiesce continued drives with basal fatigue. The altitude ascendancy arrangement - dual-zone standard, amateur (rear controls) alternative - is one of the best I've experienced, with air-conditioned air about immediately, alike afterwards the car sat anchored alfresco in 90-degree temperatures for a brace of days. The rear bench has allowance for six-foot adults, and the accepted 60/40 breach and flip-and-fold-flat cushions and seatback accomplish burden assignment easy.

SAFETY: M-Class cartage are amidst by a able axial assurance corpuscle and advanced and rear crumple zones. Acceptable four-wheel disc brakes are aided by a four-channel antilock arrangement and Anchor Assist. The accepted 4ETS four-wheel drive arrangement includes absorption control, and the ESP cyberbanking adherence accessory arrangement is accepted equipment. Dual-stage advanced airbags, advanced and rear ancillary airbags, side-curtain airbags and a roll-over sensor are all accepted equipment.

RIDE AND HANDLING: The aboriginal M-Class was one of the best-handling SUVs, and Mercedes-Benz has alone bigger aloft that. With a lighter and added adamant unibody anatomy structure, and revised fully-independent bifold wishbone front, multilink rear suspension, it is amid the best car-like of SUVs in its ride and administration abilities on the road. The alone time it's accessible to acquaint the ML is not a affluence car is over artery amplification joints and added aciculate jolts, aback the accumulation of the ample auto and tires (here 255/50 HR 19 on admixture rims) makes its attendance known. And alike that is chastened compared to abounding added SUVs. Attention to aerodynamics not alone allowances ammunition economy, it additionally after-effects in low levels of wind babble and acceptable adherence in able winds.

PERFORMANCE: Avant-garde agent cartage are neither apathetic nor noisy, and the ML 320 CDI is a accomplished example. With a 0-60 time of 8 seconds, it won't authority up traffic, and, except for a chastened bang aback cold, it could be aloof addition gasoline-powered SUV. Clouds of charcoal are absent, acknowledgment to the blaze agitator and chapped filter. Construction of the 3.0 liter V6 is little altered from a avant-garde gasoline engine, with aluminum admixture bifold aerial cam active with four valves per butt and an aluminum admixture block with adamant butt liners. The variable-nozzle turbocharger and air-to-air intercooler could additionally be acclimated in a gasoline engine. But a 16.5:1 compression arrangement and high-pressure (22,700 psi!) common-rail ammunition bang with piezo-ceramic ammunition injectors are aerial tech, agent style. Ceramic afterglow plugs are acclimated for starting in algid weather; with temperatures never beneath 70 alike at night during my time with it, the CDI started as bound as any avant-garde gasoline vehicle. If the application appraisement of 215 at 3800 rpm doesn't assume any bigger than an earlier naturally-aspirated 3.0-liter V6, the 398 lb-ft of torque accessible from 1400 through 2800 rpm accommodate able dispatch and towing ability. EPA breadth is 18/24, and if I accept the cruise computer, I got about 20 in boondocks and over 24 at a abiding 70 or so on the accessible road. Cartage may appetite to stop afore the ML needs to. The seven-speed automated manual uses adaptive argumentation to "learn" the driver's appearance and about-face accordingly, and works altogether able-bodied in D. Also, the manual has assorted about-face modes, for use in off-road and aback towing. The full-time four-wheel drive arrangement splits torque 50/50 front/rear in accustomed operation, with added activity to the arbor that can best use it, and caster ascendancy via the ESP argumentation and agent and alone anchor modulation.

CONCLUSIONS: With apple-pie agent power, an off-road able SUV can be fuel-efficient and civilized. Best archetype yet: the 2008 Mercedes-Benz ML320 CDI.

SPECIFICATIONS

2008 Mercedes-Benz ML 320 CDI

Base Price $ 44,650

Price As Tested $ 60,860

Engine Type turbocharged and intercooled dual

overhead cam 24-valve aluminum alloy

72-degree agent V6 with antithesis shaft

and common-rail absolute ammunition injection

Engine Size 3.0 liters / 182 cu. in.

Horsepower 215 @ 3800 rpm

Torque (lb-ft) 398 @ 1400-2800 rpm

Transmission 7-speed automatic

Wheelbase / Length 114.7 in. / 188.5 in.

Curb Weight 4,817 lbs.

Pounds Per Horsepower 22.4

Fuel Capacity n/a gal.

Fuel Requirement ultra-low sulfur agent fuel

Tires 255/50 R19 107H Michelin

Brakes, front/rear vented disc / solid disc,

ABS, BAS, ESP standard

Suspension, front/rear independent bifold wishbone /

absolute multilink

Ground clearance 8.3 inches

Drivetrain in-line advanced engine,

single-range 4-wheel drive

PERFORMANCE

EPA Ammunition Abridgement - afar per gallon

burghal / artery / observed 18 / 24 / 24

0 to 60 mph 8.0 sec

Towing capacity 7200 lbs.