It’s not a new argument but it’s still a solid one. If the goal is to leave more oil in the ground and spew less carbon into the air, better to frugal-ize thirsty vehicles that sell in vast numbers (read: big trucks) than develop extreme gas-sippers nobody wants to buy (read: little cars).
On that basis, the low-hanging fruit is the full-size pickup. The proven fuel economy of diesel engines is available from all the Detroit brands, now that GM has added the option on its new-last-year Chev Silverado and GMC Sierra siblings.
According to government testing, GM’s 3.0-litre DuraMax turbo-diesel promises 15 per cent lower fuel consumption than the most frugal gas model, and almost 30 per cent lower than the 6.2-litre V8 which it matches for torque.
We pitted a 2020 GMC Sierra diesel against a 2020 Ram 1500 EcoDiesel, which recently returned to market after a two-year hiatus (Ram first offered it in 2014). Ford has also offered a diesel on the F-150, but a test sample was not available for this match-up.
Ram arguably initiated the menacing, incredible-hulk grille trend in pickups, but it seems less in-your-face these days. The test sample, a Rebel, wore off-road oriented trim and all-terrain tires, augmented with optional black powder coated front bumpers and Sport performance hood.
The Sierra’s blunt battering-ram snout takes the aggressive look to new heights, and on the test vehicle is supplemented by the Elevation trim that pursues a “street-smart” theme with styling cues that include black-painted 20-inch wheels and other black accents, including the grille.
Truly sumptuous décor is available in some of Ram’s higher trims. The Rebel’s is more functional, but still features soft surfaces with real stitching. Visibility factors aren’t quite as good as in the Sierra, and the gauges could be clearer, with a DEF gauge replacing the gas models’ water temp gauge. We like the rotary-knob gear selector and multi-configurable centre console storage, but what really sets the Ram apart is its 12.3-inch vertical display screen. It can be a mild pain having to navigate menus on-screen to switch on the seat heater or find the water temperature (in the gauge cluster). On the other hand, it helps keep the number of hard switches to a manageable level.
The Sierra’s cockpit is relatively traditional and business-like. The shifter is a stout lever on the steering column and there’s a real set of six clear, finely calibrated gauges. The touch-screen is no more than an 8-incher even on higher trims. There’s less reliance on the screen for commonly-used functions, but on the other hand the sheer number of hard buttons is a little daunting, and the screen-based “virtual” buttons are smaller and harder to locate accurately.
The Ram has a little less power (260 hp) than the GMC but a tad more torque (480 lb.-ft.) which should make it a wash against the stopwatch. But the Ram has fewer gear ratios, weighs about 200 kg more, and suffers significant turbo lag. Launching hard off the line, that translates into a difference you can feel -- more than a second slower (9.7 second) to 100 km/h. Once you’re rolling, you don’t notice any performance deficit, and the Ram’s engine is noticeably quieter than the GMC’s when working through the gears. Cruising the highway at 120 km/h, however, the Ram (on its optional 3.92 axle) is spinning almost 500 rpm faster than the GMC, and sounds noticeably busier. Chassis-wise -- even without the optional air springs -- the Ram’s unique-in-segment coil-spring rear suspension rounds off bumps better than its leaf-sprung rivals and almost never gets thrown sideways by the biggest craters. And while the Ram’s cornering persona may be correspondingly softer than the Sierra’s, it’s still remarkably deft and easy-handling for something of its size and weight.
Never mind the test-bed numbers: on the road, when a light turns green and your right foot goes down, turbo boost spools up much faster in the Sierra. Keeping it planted, we saw 100 km/h arrive in 8.5 seconds. In the process, you’ll hear a little more under-hood ruckus than in the Ram, but nothing you can’t live with. And the engine fades out almost completely once you’re up into 10th gear in the highway; at 120-km/h it’s just whispering along at about 1,500 rpm. Straight-line speed isn’t the only reason the Sierra is more engaging to drive; it also handles improbably well for its size, its steering so light and precise that we’d almost call it dainty. Conversely, the stiff ride is all macho -- including the rear axle’s sideways skitter on severe road rumples.
Almost all contemporary connectivity, infotainment and driver-assist features are available, including semi-automated parking, and blind spot monitoring with trailer coverage.
Sierra matches Ram on connectivity, infotainment and driver-assist, plus offers trailering aids like multiple cameras to facilitate hitch-up, trailer-lights test and towing.
There’s no regular-cab Ram, so, no 8-foot box (shop the Ram Classic for that). The choices are 5-ft 7-in or 6-ft 4-in boxes on the Crew Cab, or the 6-ft 4-in only on the Quad. Cargo-bed options include lockable bins, and a 60/40-split tailgate that can fold down conventionally, or swing out laterally. Peak tow rating for any Ram 1500 diesel is a whopping 12,560 lbs (4x2 Quad Cab tradesman); for the popular 4x4 Crew Cab configuration, 9,710 lbs is the tow limit.
The Sierra’s 2019 redesign brought segment-leading box volumes, about 21 per cent more than the Ram equivalent for the 5-ft 8-in box, 16 per cent more for the 6-ft 6-in. You can still get a Sierra with a regular cab and 8-ft box (though not with the diesel). Sierra options include a carbon-fibre box, and GMC’s Swiss-Army-Knife interpretation of a multi-function tailgate. Top diesel tow rating is 9,100 lbs (for a Double Cab 4x4), or 9,000 for a Crew Cab 4x4.
And the fill-‘er-up bottom line? Both trucks deliver near-miraculous fuel consumption for their bulk and mass. According to their window stickers, the Ram rates 9.7L/100 km combined, versus the Sierra’s 9.9. However Sierra’s lighter and more aero Chevrolet twin scores 9.4 in the same test. Over the course of my mid-winter real-world test, the trip computers called it Ram 10.9, Sierra 11.0.
So let’s call the fuel-economy comparison a tie. What matters is, whichever you pick, the diesel option will keep more carbon out of the air and more gas money in your pocket. That said, if you value comfort and refinement, you’ll be happier at the wheel of the Ram. If you want a truck that’s more fun to drive, head for the GMC (or Chevrolet) store.
GMC Sierra Duramax Diesel
Price: (min/as tested): $52,998/$65,533
Engine: 3.0-litre In-line 6-cylinder turbo-diesel
Fuel Consumption (L/100 km): 10.5 city/9.1 hwy
Alternatives: Chevrolet Silverado, Ford F-150, Ram 1500
Ram 1500 EcoDiesel
Price (min/as tested): $49,945/$76,745
Engine: 3.0-litre V6 turbo-diesel
Transmission/Drive: 8-speed automatic/4x4
Fuel consumption (L/100 km): 11.1 city/8.0 hwy
Alternatives: Chevrolet Silverado, Ford F-150, Ram 1500
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