As GM Authority has covered in the past, the ongoing global microchip shortage has resulted in lost production and the removal of several features, including the removal of automatic engine stop-start from GM’s line of full-size 2021-model-year SUVs. Now, GM Authority is taking a closer look at how the removal of automatic engine stop-start affects the fuel economy for the 2021 Chevy Tahoe.
For readers who may be unaware, automatic engine stop-start is a feature that automatically stops a vehicle’s engine when the vehicle comes to a stop, such as in heavy traffic or at a stop light. Once the driver removes their foot from the brake pedal, the system automatically restarts the engine, thus enabling the vehicle to once again get under way.
The system is designed to lower emissions and increase fuel economy. However, due to the global microchip shortage, the feature was removed from certain 2021 Chevy Tahoe models produced after June 7th, 2021.
Affected models include those equipped with the naturally aspirated 5.3L V8 L84, rated at 355 horsepower and 383 pound-feet of torque, and the naturally aspirated 6.2L V8 L87, rated at 420 horsepower and 460 pound-feet of torque. Both engines connect to a 10-speed automatic transmission.
The 2021 Chevy Tahoe is also offered with the 3.0L I6 LM2 turbodiesel Duramax, which is rated at 277 horsepower and 460 pound-feet of torque, and also connects to a 10-speed automatic transmission. Models equipped with the LM2 continue to feature automatic engine stop-start.
Overall, the fuel economy differences are relatively minor between 2021 Chevy Tahoe models equipped with automatic engine stop-start, and equivalent models without the feature, with just a single mpg difference in the city and combined, depending on the configuration.
Check out the full fuel economy breakdown in the table below:
| Drivetrain | Engine | Transmission | Auto Stop/Start | City mpg | Highway mpg | Combined mpg | Effective Date |
|---|---|---|---|---|---|---|---|
| 2WD | 5.3L V8 L84 | 10-speed auto | Yes | 16 | 20 | 18 | Start of 2021 MY |
| 2WD | 5.3L V8 L84 | 10-speed auto | No | 15 | 20 | 17 | June 7, 2021 |
| 4WD | 5.3L V8 L84 | 10-speed auto | Yes | 16 | 20 | 18 | Start of 2021 MY |
| 4WD | 5.3L V8 L84 | 10-speed auto | No | 15 | 20 | 17 | June 7, 2021 |
| 2WD | 6.2L V8 L87 | 10-speed auto | Yes | 15 | 20 | 17 | Start of 2021 MY |
| 2WD | 6.2L V8 L87 | 10-speed auto | No | 14 | 20 | 16 | June 7, 2021 |
| 4WD | 6.2L V8 L87 | 10-speed auto | Yes | 14 | 19 | 16 | Start of 2021 MY |
| 4WD | 6.2L V8 L87 | 10-speed auto | No | 13 | 19 | 16 | June 7, 2021 |
| 2WD | Turbodiesel 3.0L I6 LM2 | 10-speed auto | Yes | 21 | 28 | 24 | Start of 2021 MY |
| 4WD | Turbodiesel 3.0L I6 LM2 | 10-speed auto | Yes | 20 | 26 | 22 | Start of 2021 MY |
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Comments
I am still amazed how GM has not figured out by adding a mild hybrid for a few thousand dollars to these large SUVs can increase the city mileage by 20 to 30%. Surely the $2,000 increase on a $70,000 vehicle can easily be paid back in the gas savings in a few years. It almost borders on criminality against the environment. And I’m not a tree hugger but there’s no common sense in upper management
The Suburban 3.0T diesel can see 35+ mpg as seen from a couple of YouTube reviewers.
The Toyota Sienna Hybrid is only getting 32.8 mpg on fuelly. And this has a buzz-bomb 4-cylinder even when not loaded!
The product must be competitive with other vehicles such as the Lincoln Navigator and a $2-3000 increase will make the Tahoe overprices in comparison. Packaging also is a factor since a hybrid would take away storage space.
I’ve seen other sites test this too and the gain with start/stop is negligible.
5-8% isn’t negligible, that is about 1mpg in city driving. Idling is one of the most wasteful times for a vehicle, so if you can get rid of that waste, that is fantastic. I wish they would go hybrid or PHEV as that can really make the start stop go to another level. Either way it works as advertised and I welcome it, I am always down to save a little money or do a small part in helping the environment.
Your buying a 5000 to 7000 pound vehicle the gas mileage on a truck this size when I was growing up was like 9 to 12 mpg going down hill… And besides a hybrid would make sense but it would also take room away from the interior space and add more complexity abd weight…. besides a few years back GM tried hybrid Tahoe’s and they bombed nobody bought them because they where so expensive. Anyhow people who buy these usually have a second car to commute in… These big boys are not commuter vehicles unless you live 10 or 15 minutes from work.
You think most of these are not commuters? Haha, most are. Very few have a second vehicle as a commuter. Of the people that I know that have owned or currently own a full size SUV (including us) not one is not using it as a daily driver/commuter. I am a big fan of hybrids, especially plug in hybrids. The torque of an electric motor, not using gas for XX amount of miles and the added power it can provide, I wish they would go this route as a transition in to the electric only because full electric isn’t feasible for many people just yet with the current infrastructure and charging capabilities. I would buy a PHEV truck (mid size particularly) GM vehicle, but I will pick ICE over electric for a future with our uses.
A win for the starter of the non auto/start nonsense vehicles.
My 2016 Honda Pilot gets 31 mpg on highway.