TRAVERSE CITY, MI – Human beings have made many grand adjustments in the past: They accepted the idea the Earth circles the sun, and not the other way around. They have acknowledged the world is round and not flat.

Could it be they finally recognize diesels no longer are noisy, smelly and slow? Recent sales figures at BMW North America LLC suggest the worm is turning.

Diesels are a staple in Europe, powering about 50% of all new light vehicles.

But in the U.S., the general consensus among critics is that Americans never will accept light-duty diesels. Compression-ignition technology is too expensive, diesel-fuel prices too volatile and diesel’s reputation too besmirched to ever catch on.

In fact, in the past year, Honda Motor Co. Ltd., Nissan Motor Co. Ltd., General Motors Co. and Ford Motor Co. all have cancelled or shelved plans to offer light-duty diesels in the U.S.

European auto makers appear to be the only ones left trying to sell diesels to U.S. consumers, and to many it’s considered a Quixotic pursuit. Yet, the hottest-selling BMW this summer is the diesel-powered X5 xDrive35d cross/utility vehicle.

The CUV has the highest pre-sold order bank of any BMW product in the U.S., says Martin Birkmann, manager-product planning and strategy at BMW North America.

No one predicted this. Not even BMW executives.

“Had you asked me about diesel prospects a year ago, I would have been a bit ho-hum, but right now we are fighting for production allocation with other markets in the world to satisfy a growing demand in the U.S.,” Birkmann says.

Demand for BMW’s other diesel-powered vehicle, the 335d, is not as strong in comparison but still double that of a year ago.

Ward’s editors are among the minority of industry observers not surprised by BMW’s success. The auto maker’s 3.0L I-6 turbodiesel has been named to the Ward’s 10 Best Engines list for the last two years.

Making 265 hp and 465 lb.-ft. (576 Nm) of torque at just 1,750 rpm, the engine delivers astonishing performance and fuel economy.

We know the engine is a superb powerplant, but we thought the 250-mile (402-km) trip from metro Detroit to Traverse City, perched along Lake Michigan on the northwest side of the state, would be a good test of the diesel’s claimed appeal in high-speed highway driving, an area where hybrid-electric vehicles can’t offer much advantage.

WardsAuto.com Associate Editor James Amend piled his young family into an X5 xDrive35d, and I drove a 335d to the CAR Management Briefing Seminars here to underscore what we and a growing number of BMW customers already know: diesels are great for road trips.

Whether cruising north on Interstate-75 or negotiating narrow 2-lane highways west across the state, the diesel’s low-end torque never ceases to impress during passing and merging.

“Barreling north to Traverse City in the X5 and watching the fuel gauge stick stubbornly on ‘full,’ the thought occurs – why do diesels have such a poor reputation?” Amend says.

“I've heard stories of the oil burners of the 1980s. Loud, smelly and belchers of black clouds of exhaust, they say. But as a kid in the 1980s, we never had any of those old beasts in the neighborhood. My initiation to the world of diesels came via BMW a handful of years ago driving in southern Germany.

“Those cars were a delight, and the X5 I've crammed my family into for MBS this week features the same 3.0L twin-turbo engine. With loads of torque, it makes quick work of passing crowded recreation traffic on I-75 and blending seamlessly back into traffic from rest stops,” he adds.

My impressions of the 335d are similar, but with the considerably lighter weight of the 3-Series, the performance is even more pronounced.

The vehicle accelerates to 60 mph (97 km/h) in 6 seconds, but does not want to stop there. Cruising up I-75 is so quiet and effortless, it’s easy to creep up to 100 mph (161 km/h) without noticing.

I set the speed control at 80 mph (129 km/h) for most of the trip. Even then, I averaged 33.6 mpg (7 L/100 km) over 260 miles (418 km). I’ve put 300 miles (483 km) on the car since BMW dropped it off on Friday, and the tank still is almost half full.

Amend is impressed by the X5’s range as well.

“What really makes a guy grin is knowing the X5 has about 500 more miles (805 km) to go before we need to replenish the fuel tank,” he says. “All told, Detroit to Traverse City, the X5 makes 25 mpg (9.4 L/100 km), and we've got it loaded to the gills with kids and gear. Try that in a Chevy Tahoe.

“Today's diesels don't deserve to be called anything but clean, efficient and durable. And I bet the folks at BMW share my suspicions that there's a lot more GenXers like myself without messy preconceptions waiting to be wowed by diesel technology. I'm sold.

“Sure, there's a bit of the old rat-a-tat-tat from the injectors under heavy acceleration. But cruising at highway speeds, the X5 is quiet as a church pew.”

Amend is not exaggerating about the lack of noise at cruising speeds. The 335d’s cabin is eerily silent on the highway, noticeably more than its gasoline-powered siblings.

On a long-trip, that peacefulness lessens fatigue. I’ve driven scores of vehicles up to Traverse City over the past 25 years, and for me this is the most relaxing drive ever.

I doubt Amend can make the same claim, but with two young children on his trip, it has nothing to do with the X5’s engine.

dwinter@wardsauto.com