We like to think of ourselves as agents of our own destinies, but behavioral science says that we simple humans can be steered toward certain decisions simply by disguising the idea that there’s a decision to be made at all. To arrive at a preferable outcome, sometimes all you need is a gentle prod in the right direction, an unnoticed prompt that often manifests in the form of a default choice. It’s called nudge theory, and auto enrollment in retirement plans is a classic example. People tend to save more money when they have to opt out of a plan rather than opt in. Now, would you like to stick with the 3.0-liter diesel in this 2021 Chevrolet Suburban or do something else? Right. Keep the diesel. Good choice.
Ah, if only General Motors auto-enrolled Suburban buyers with the diesel. Were the Duramax inline-six the default option across the line, most Suburbans would likely be diesel-powered. And that would be right and proper, because the 3.0-liter six is perfectly adapted to Suburban duty. Its 460 pound-feet of torque arrive at only 1500 rpm, imbuing the 6272-pound behemoth with an air of nonchalant muscularity in real-world driving. Even in the rare foot-to-the-floor sprint, the diesel Suburban doesn’t feel slow, recording an 8.4-second run to 60 mph. The Duramax’s relative paucity of horsepower—277 horsepower at 3750 rpm—shows up in the tepid quarter-mile stats, with our High Country model crossing the line in 16.5 seconds at 85 mph. But that kind of performance is more than fine for a Suburban, where the horses you’re towing are more important than the ones under the hood. Maybe you want a baritone V-8 and scorching acceleration in a Tahoe RST or a GMC Yukon Denali or a Cadillac Escalade, but the Suburban is inclined toward milder pursuits. The High Country with a 420-hp 6.2-liter V-8 will go from zero to 60 mph in 6.1 seconds, but we bet few ever will. A Suburban has too many beverages in too many cupholders for those kinds of shenanigans.
Plus, the Suburban joins its full-size-SUV GM kin in its aversion to lateral acceleration. Like the Tahoe, Yukon, and Escalade, the Suburban’s stability control system is programmed to intervene at an absurdly low threshold. Forget tossing this thing into a choice on-ramp. You might get slapped down for going too hot into the left-hander at the Taco Bell drive-through. Thus, as with the other full-size GM SUVs, we had to run our skidpad test in low-range four-wheel drive, as that’s the only way to defeat the stability control system. But the diesel models, unlike their gas-powered counterparts, run into a 35-mph speed limiter in low range, which means that the diesel Suburban can only manage a top-speed-limited 0.53 g of lateral acceleration. We humbly suggest that if your vehicle can only pull 0.53 g, then perhaps 277 horsepower is sufficient.
It certainly feels that way when the Duramax-powered Suburban is in its element—which is to say, highway driving. With that luxurious 134-inch wheelbase and four-wheel independent suspension, the Suburban glides imperiously down interstates, whether perched on its base steel springs or the optional air suspension with magnetic ride control. At 70 mph, a hushed 67 decibels find their way to the cabin—the same noise level as the Lexus ES350 that we described as cryptlike. Most of that seems to be wind and tire noise, the straight-six emitting no more than a distant thrum from somewhere beyond the firewall, happily firing the gargantuan Chevy down the road while the tachometer needle hangs out down near idle.
We didn’t get a chance to run our 75-mph fuel-economy test on this Suburban, but when we ran its shorter Tahoe sibling, we got 27 mpg. Both Tahoe and Suburban get the same EPA numbers, which bear out the 3.0-liter’s righteous frugality. Among four-wheel-drive Suburbans, the diesel gets better city mileage than the gas engines manage on the highway. And those 4WD EPA numbers—20 mpg city, 26 mpg highway—might undersell the diesel’s efficiency, depending on what kind of driving you do. On a 45-mile backroads jaunt, the Suburban’s trip computer showed 32.3 mpg. We don’t always trust a car’s assertion of its own wonderfulness, but in this case, we wouldn’t be surprised if the computer was honest. After 300 miles of mixed driving, the fuel gauge was still above half a tank.
When you do finally have to fuel up, the Suburban offers a capless filler, a treat for a diesel. Too bad diesel pump handles still tend to be coated with the unctuous slime of petrochemical prehistory, but at least you won’t have to handle them too often. Next to the filler neck is the blue cap for the diesel-exhaust fluid, which you will need to add occasionally to keep emissions in check.
The diesel can also tow as much as 8000 pounds (in the same ballpark as the gas models), with a standard exhaust brake adding some big-rig trailer-towing confidence. There’s really no obvious downside to the compression-ignition Suburban—no uncouth clatter, no dearth of power, no huge price penalty. In fact, in High Country trim, like our test vehicle, the Duramax engine is actually $1450 cheaper than the standard 6.2-liter V-8. In the rest of the trims—LS, LT, RST, and Premier—it adds $1045 to the price.
Even on the High Country, where it comes with a discount, the Duramax isn’t the default choice. But it ought to be, across the board. If GM wants its customers to see the Suburban in the best possible light—thrifty, torquey, quiet, and smooth—all it needs to do is give them a little nudge.
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