There is a multitude of SUVs and crossovers available to serve the needs of the motoring public. They range vastly in price, performance and efficiency. At the upper end of the price range sits the mid-size ML from Mercedes-Benz, which was launched in 1998; the present generation of this upscale all-wheel-drive (AWD) rig greeted us in 2006. This week's example is diesel-powered, making it fairly unique within the broader SUV/crossover segment.

The ML320 CDI is in every way a premium-level SUV.

Can I live with a diesel?
Likely this fundamental question floats through the mind of many a prospective diesel purchaser. How it's answered undoubtedly guides the decision to buy an oil burner or not. Some quick comment: today's diesel technology is immensely better than it was only five years ago; gone in most cases is the incessant clatter and the smoke and fumes.

During my test period, the only annoyance that crept into my divine motoring was determining where the most convenient dealers of diesel stood within my typical range of driving. As diesel gain popularity, diesel-equipped service stations will likely keep pace. At this juncture in history, I had to deviate from my normal routing to fill the ML's tank at a single diesel pump among a plethora of gasoline pumps.

I was dismayed to find that a fraction of my outstanding fuel economy was eroded by the higher price of diesel over that of regular unleaded- it seems to average 5-6 cents more per litre. So the "living with diesel" dilemma isn't so much about the vehicle anymore as it is about the cost and convenience of diesel. Nevertheless, for the right vehicle with the right diesel technology, I could tolerate the secondary annoyances.

What makes the ML320 CDI so special that I would go out of my way to fill it, and pay more in doing so you ask?

The easiest way to answer that question is to flippantly reply, "go drive it," but of course that's my job, so I better get to work. In short, the turbocharged 3.0-litre DOHC V6 diesel at work in the ML320 produces a torque rating that any V8 engine would be proud of while delivering fuel economy consistent with an efficient V6 or even a four-cylinder engine.

If you think the diesel burner is a slug when it comes to acceleration, think again.

In fact, at 398 pound-feet, this diesel mill generates more torque than the new 5.5-litre V8 that Mercedes-Benz offers in the ML as a high performance gas engine; the V8 produces 391 pound-feet @ 2,800 rpm while the small diesel burner produces its maximum torque @ only 1,600 rpm. Granted, the big-8 conjures-up 382 horsepower while the diesel V6 dispatches far less at 215 ponies.

In the ML 320 CDI, the diesel operates with the utmost in discretion.

But let's take the comparison a step further and examine fuel economy ratings if we dare. The ML320 CDI receives an EnerGuide Canada rating of 11.3 and 8.3 litres of fuel per 100K of city and highway driving respectively (25/34 mpg) while the V8-powered ML550 is rated at 16.0 and 11.2 litres (18/25 mpg) of premium gasoline for the same distances. That's compelling.

One final nail in the V8's coffin: the ML320 CDI and the ML550 are equally tow-rated at 3,265 kg (7,200 lbs). And if you think the diesel burner is a slug when it comes to acceleration, think again. Mercedes-Benz claims it'll put 100-kph on the clock in just 8.6 seconds, and that's respectable for any large SUV.

Taking the ML320 CDI on the road
Stepping into the throttle from any speed nets very strong acceleration- more so than expected, especially off-the-line. The ML is equipped with a sophisticated 7-speed transmission, which ensures there is a wide cache of gearing available to match immediate needs, whether such needs pertain to economical cruising or robust acceleration.

Small rocker switches on the back of the steering wheel allow the driver to manually operate the transmission with his/her fingertips. This feature is remarkably convenient, and encourages the use of engine braking when slowing down or coming to a stop.

The ML320 CDI is quite a polished performer. The diesel operates with the utmost in discretion, only announcing itself in any meaningful way when asked to perform. Otherwise, the beautifully executed cabin is a place of serenity complemented by a relatively smooth but always composed ride quality.

The beautifully executed cabin is a place of serenity.

The ML320's body structure and chassis feel tightly unified, generating no squeaks squawks or thumps as sometimes found in SUVs. Steering response is better than typical of the segment as is the ML320's ability to handle a twisty road with enthusiasm.

The ML320 CDI is quite a polished performer.

Although strong and capable, it took me some time to become accustomed to my tester's brake pedal; it felt a little on the mushy side and was more sensitive than suitable for a brute such as me. Also, I found the on-board navigation system to be less intuitive to operate than others I have sampled. Acura's setup being one such example.

Finalizing the diesel decision
The ML320 CDI is in every way a premium-level SUV. It spoils its occupants with attributes such as quality, comfort and luxury. And it does so while cleanly burning frugal amounts of diesel fuel in return for prodigious power output. And that makes it a winner despite an over-bearing "as tested" price tag of $71,875.