The full-size, 2015 GMC Yukon Denali is a no-excuses sport utility vehicle that’s both capable and pampering.

The fuel-thirsty SUV – updated this year with more luxury features, a more powerful engine and new styling – also is well-timed, as declining U.S. gasoline prices have reached a four-year low and are still falling.

With a towing capacity of 8,300 pounds, the Yukon Denali can pull heavier trailers than a full-size Mercedes-Benz GL-Class SUV. And the big GMC swallows luggage in a cavernous, 121.1-cubic-foot cargo area that is 29 percent larger than the Mercedes.

Tall drivers and front passengers can revel in the nearly unheard-of 45.3 inches of legroom. That’s 5 inches more than what’s offered by the Mercedes’ GL-Class.

The Yukon and its premium version, the Denali, are built for large families, trailer haulers and anyone else needing really roomy, luxurious and stout transportation. But they have some faults.

Fuel mileage, of course, is not the best in this 17-foot-long, two-ton-plus SUV. The best federal government fuel economy rating for the 2015 Yukon Denali is 15 miles per gallon in city driving and 22 mpg on the highway for a two-wheel drive model.

And, base price is up some $4,400 from the 2014 model. Starting manufacturer’s suggested retail price, including destination charge, is $64,965 with 420-horsepower, gasoline V-8, new eight-speed automatic transmission and rear-wheel drive.

The lowest starting retail price, including destination charge, for a 2015 Yukon Denali with four-wheel drive is $67,965.

But the Yukon Denali comes well-stocked.

Standard equipment includes 10-speaker Bose premium surround sound, Bluetooth hands-free phone connectivity and audio streaming, perforated leather-trimmed seats, power-adjustable brake and accelerator pedals, power liftgate, power-folding third-row seats, heated outer second-row seats, heated and cooled front seats, three-zone climate control, luggage rack, remote vehicle start, rearview camera and heated and leather-wrapped steering wheel.

There are unexpected features, too, such as five 12-volt power outlets, a handle at every door entry and an articulating display screen in the middle of the dashboard that has hidden storage.

Competitors in the Yukon Denali’s price range and full-size category include luxury SUVs. A new Mercedes GL SUV has a starting retail price of $64,525 with all-wheel drive, a 240-horsepower, diesel six cylinder and seven-speed automatic. And a 2015 Ford Expedition King Ranch model with two-wheel drive starts at $58,185 with 365-horsepower, gasoline V-6 and six-speed automatic.

The Yukon Denali has a personality all its own, though its truck platform and many other mechanical parts are shared with production line siblings Chevrolet Tahoe and Cadillac Escalade.

Among the three, the Yukon Denali is the best combination of rugged authenticity and luxury. The ride is truck-like, yet cushioned. Magnetic Ride Control is standard, and it smartly manages the weight and weight shift of the vehicle. Best of all, Magnetic Ride Control keeps bumps from making a big impact. There was no jarring hit from road bumps, even on degraded off-road trails.

With slow speed and patience, the Yukon Denali kept everyone coddled as it navigated deep holes and rocky areas.

The Denali interior is surprisingly hushed, thanks to acoustic engineering. It was easy to hear passengers in the test Denali third-row seat talking. No one had to shout.

Even better, on long highway runs, wind noise – which can become fatiguing – was muted.

The 6.2-liter, overhead valve V-8 with variable valve timing gave strong power, but it wasn’t instantaneous in this heavy SUV. Rather, torque peaks at 460 foot-pounds at 4,100 rpm, so a driver feels - and hears - a mounting surge of power coming on steadily.

At highway speeds, the Yukon Denali traveled almost leisurely. The V-8 had more power to give than what was needed for today’s speed limits.

Fuel mileage, however, for the four-wheel drive test vehicle was just under 16 mpg, which is the federal government’s average for city/highway travel of this model.

The Yukon Denali carries a big fuel tank holding 26 gallons, but this translated into just over 400 miles of travel range. And even with gas prices at a low point, it cost $79 to fill.

GMC notes that premium gas is recommended but not required.

Large-sized passengers will love that seats in the first two rows are sizable and well-cushioned.

Door entries are large-sized, too, to help passengers get in and out easily.

Small-statured passengers did best, though, with the test vehicle’s optional running boards. They activated noisily as they slid out and then slid back under the vehicle on each side. They also were illuminated at night.

One unusual item was the Yukon Denali’s old-style, steering column-mounted shift lever.

Standard safety equipment includes a middle-of-the-front-seat air bag that is designed to reduce injuries in side crashes.

Also standard: Front and rear park assist, side monitor and lane change alert.

The 2015 Yukon Denali is rated four out of five stars overall in federal government crash tests. Passenger protection in frontal and side crash tests was the best at five stars. But the potential for the high-riding SUV to roll over garnered three out of five stars.

Consumer Reports rated reliability of the new Yukon at average.