The Cost of Comfort: GM's Full-size SUVs Gain Thrift in City Driving, Lose It on the Open Road

Steph Willems
by Steph Willems

The revamped, full-size Chevrolet Tahoe and Suburban and their GMC Yukon/Yukon XL twins gain significant length, interior volume, and creature comforts for 2021, but extra MPGs seem to be in short supply.

The vehicles are now even larger than their predecessors, are still heavy, and carry identical V8 engine displacements, so no one should have expected Prius fighters. Still, the changes in fuel economy are worthy of note.

Still unlisted on the EPA’s fuel economy site, the models had their MPG figures released by GM this week. What we can see is that, while efficiency sees a gain in the city, that improvement is offset by decreased thriftiness on the highway.

It breaks down like this: in 5.3-liter, RWD or 4WD, short-wheelbase guise, the 2021 GM full-sizers rate 16 mpg city, 20 mpg highway, and 18 mpg combined. The previous-generation 5.3L short-wheelbase models earned 15/22/18 in rear-drive guise, 15/21/17 with four-wheel motivation.

The lengthier 5.3L models match these figures in rear-drive form, but lose 1 MPG in each driving cycle when equipped with four-wheel drive. EPA ratings for the old-gen 5.3L long-wheelbase models stand at 15/22/18 (RWD) and 14/21/17 (4WD).

Inclusion of a standard 10-speed automatic and GM’s Dynamic Fuel Management helped the V8 manage its thirst around town, but it seems all the new added hardware (tech niceties, independent rear suspension, size) causes the hulking SUVs to imbibe more heavily on the highway. Highways are for AAA, not AA, it seems.

Opt for the 6.2-liter in either the Tahoe or Suburban, and the EPA rating comes out to 16/20/18 regardless of driveline type. No penalty here for going bigger (minus the cost, of course). The new models in 6.2L guise slightly top their predecessors in both city and combined economy.

It all sounds unimpressive, until you consider GM’s decision to offer the company’s new 3.0-liter Duramax inline-six diesel in all such models (including the Cadillac Escalade). Boasting 277 horsepower and 460 lb-ft of torque, the Duramax variants’ MPG rating remains unknown, but one look at the Chevy Silverado’s ratings suggests significant improvements in efficiency for so-equipped models. Chris was pleased with what he saw in a recent test of a new Duramax-powered Silverado 1500.

[Images: General Motors]

Steph Willems
Steph Willems

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  • RSF RSF on May 07, 2020

    No one cares about a MPG rating on these. What matters to me, much more than ever, is how much of this thing consists of Chinese parts.

  • Jerome10 Jerome10 on May 07, 2020

    Do I have it right that these went from AFM (4 or 8 cylinder only) to DFM (any cylinder combo from 1-8 at any time) and went from 6 speed to 10 speed transmissions.... And got basically zero MPG improvement? If so why bother? And if this isn’t an indication we’re scraping the bottom of the barrel when it comes to ICE and transmission efficiency gains I’m not sure what is.

  • Dave M. The Outback alternates between decent design and goofy design every generation. 2005 was attractive, 2010 goofy. 2015 decent. 2020 good, but the ‘23 refresh hideous.Looking forward to the Outback hybrid in ‘26…..
  • Lorenzo Subaru had the ideal wagon - in 1995. The Legacy Outback was a straight two-box design with rear quarter and back windows you could see out of, and was available in brown with a 5-speed manual, as God and TTAC commenters intended. It's nice they're not raising prices, but when you've lost the plot, does it matter?
  • Bkojote Remember a month a go when Cleveland wanted to create a more walkable Cleveland and TTAC's 'BIG GOVERNMENT IS THE PROBLEM' dumbest and dullest all collectively crapped their diapers? Here's the thing- look on any American highway and it's littered with people who don't /want/ to be driving or shouldn't be. Look at every Becky on her phone during the morning commute in her Tucson, look at every Brad aggro driving his 84 month loan GMC. Hell look how many drivers nowadays can't even operate a headlight switch. You expect these people to understand a stoplight? In my neighborhood alone 4 people have been rear ended at lights from someone on their phone. Distracted driving over the past 10 years has spiked, and it's only going to get worse unless Becky has an alternative, because no judge is going to pull her license when 'she needs it to get to work!' but heaven forbid she not check fb/tiktok for 40 minutes a day.
  • Scott Shouldn't the The Italian Minister for Business be criticizing The Milano for being too ugly to be Italian?Better use of resources doing that....
  • Steve Biro Frankly, while I can do without Eyesight and automatic start-stop, there is generally less B-S with Subarus in terms of design, utility and off-road chops than with many other brands. I just hope that when they adopt Toyota’s hybrid system, they’ll also use Toyota’s eCVT.
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