Used 2021 Mercedes-Benz GLS for Sale nearWilliamsport, PA

How much does the 2021 Mercedes-Benz GLS cost?

Prices have softened 9.52% compared to this time last year, making it a favorable time to shop this model year.

There are 848 listings available, which gives you a solid amount of inventory to compare.

Is the 2021 Mercedes-Benz GLS a good car?

Yes — the 4.7/5 user rating and 8.3/10 expert rating both point to a strong overall appeal. The GLS is positioned as a luxury-first full-size SUV, and it backs that up with three rows of spacious seating, a comfortable cabin, and enough cargo room for everyday family use and bigger hauls. The model scores 9/10 across Look and feel, Performance, Technology, and Safety.

The trade-offs are clear: the third row is cramped, the technology can be unintuitive, and fuel economy is poor. That means you should like this SUV most if you want a premium, comfort-focused family hauler rather than a purely practical one.

There are 37.9% good or great deals in the market, which suggests you can still find attractive pricing if you shop carefully.

Is the 2021 Mercedes-Benz GLS reliable?

Owners rate it 4.7/5, a strong signal of long-term satisfaction. The GLS is built around comfort and upscale execution, and the expert review also points to a composed, refined driving experience with strong performance across its lineup. Its standard mild-hybrid system supports the powertrains, and the model’s overall design emphasizes smoothness and luxury over rough-edged utility.

The performance content also notes that the EQ Boost system can add extra power when needed and help spool the turbochargers more quickly. For used buyers, the main long-term ownership risk is that a complex luxury SUV can be costly to keep in top shape if prior maintenance has been neglected.

What should I look for when buying a used 2021 Mercedes-Benz GLS?

Accident-free inventory is solid at 82.1% — always verify the vehicle history report.

You should still check the vehicle history carefully, because a clean listing percentage does not replace a proper report. Prioritize a pre-purchase inspection that focuses on electronics, suspension behavior, and interior condition, since this is a tech-heavy luxury SUV. Pay close attention to how the cabin controls work and whether all comfort and convenience features operate as expected.

Key things to evaluate:

• Trim level: The GLS is available in three levels: GLS 450, GLS 580, and the Mercedes-AMG GLS 63 performance model. The GLS 450 includes remote keyless entry, remote start, nine USB ports, dual-zone automatic climate control, heated front seats, a power liftgate, wireless device charging, Apple CarPlay, Android Auto, satellite radio, and a 13-speaker Burmester premium sound system. The GLS 580 adds V8 power, heated-and-cooled front seats, massaging front seats, illuminated running boards, soft-close doors, and five-zone automatic climate control. The AMG GLS 63 adds more aggressive bodywork, quad-outlet exhaust, and a performance-inspired interior. The GLS 450 is the best-value starting point if you want the core luxury features without stepping up to the pricier variants.
• Powertrain: The GLS 450 uses a twin-turbocharged 3.0-liter inline-six with 362 horsepower and 369 pound-feet of torque. The GLS 580 uses a twin-turbocharged 4.0-liter V8 with 483 hp and 516 lb-ft. The AMG GLS 63 uses a hand-crafted 4.0-liter twin-turbo V8 with 603 hp and 627 lb-ft. All engines include Mercedes’ EQ Boost 48-volt mild-hybrid system.
• Safety package: Standard safety equipment includes Active Brake Assist, forward-collision avoidance, rain-sensing wipers, blind-spot monitoring, automatic high beams, automatic parking assist, a surround-view camera system, a driver-drowsiness monitor, and crosswind assist. Available features include lane-keep assist, lane-change assist, adaptive cruise control, a following-distance indicator, and stop-and-go cruise control.
• Infotainment: The GLS uses the MBUX system with a massive touch screen, a trackpad controller, Apple CarPlay, Android Auto, and voice control. The system is designed around large, easy-to-read icons and a fully digital instrument panel, but it does require a USB-C cable for phone connection.
• Fuel efficiency: The six-cylinder GLS 450 returns 20 mpg city, 24 highway, and 21 combined. The GLS 63 returns 14 mpg city, 18 highway, and 16 combined.

Which 2021 Mercedes-Benz GLS trim should I buy?

The 2021 Mercedes-Benz GLS is offered in 3 trim levels: GLS 450, GLS 580, and Mercedes-AMG GLS 63.

Here's the short version:

• GLS 450: This is the trim to start with if you want the GLS experience at the lowest entry point. It already brings a long list of standard luxury and tech features, including heated front seats, wireless charging, Apple CarPlay, Android Auto, and the Burmester audio system.
• GLS 580: This is the step-up choice if you want more power and more comfort features. The V8, massaging front seats, heated-and-cooled front seats, soft-close doors, and five-zone climate control make it the most appealing upgrade for buyers who want a richer daily-driving experience.
• Mercedes-AMG GLS 63: This is the performance-focused choice. It adds the most power, the most aggressive styling, and a more dramatic driving character, so it makes sense if you want the top-end version and are willing to pay for it.

Safety content notes that the GLS comes standard with a broad driver-assistance suite, while additional features such as adaptive cruise control and lane-keep assist are available.

Is now a good time to buy a used 2021 Mercedes-Benz GLS?

This is a moderate market for selective buyers, with enough inventory and deal activity to make shopping worthwhile.

• Deal availability: 37.9% of listings are priced as good or great deals.
• Inventory: There are 848 listings available.
• Price trend: Prices have softened 9.52% compared with last year.
• Clean inventory: 82.1% of listings are accident-free.

If you find a listing below $45,637, that's toward the low end of the year-round range and worth acting on quickly.

What is the 2021 Mercedes-Benz GLS's resale value?

The current average of $46,108 sits slightly below last year's $50,962.

That price movement suggests the market has cooled, which can work against a future seller if you buy at the wrong point in the cycle. On the other hand, the current softness may help you enter at a more favorable price, which can reduce the amount of value you need to recover later. If you keep the vehicle in strong condition and maintain it well, you improve your odds of holding onto more of that value over time.

Vehicles with strong owner satisfaction ratings, like this model year's 4.7/5, tend to retain buyer demand, which supports resale value over time.

Is the 2021 Mercedes-Benz GLS safe?

The GLS earns a 9/10 safety score from our experts.

It comes standard with Active Brake Assist, forward-collision avoidance, rain-sensing wipers, blind-spot monitoring, automatic high beams, automatic parking assist, a surround-view camera system, a driver-drowsiness monitor, and crosswind assist. Available safety tech includes lane-keep assist, lane-change assist, adaptive cruise control, a following-distance indicator, and stop-and-go cruise control.

Should I buy a 2021 Mercedes-Benz GLS or consider a different year?

If you're weighing the 2021 against nearby model years, here's how to think about it:

Choose the 2021 if:

• 37.9% of listings are priced as good or great deals.
• Accident-free inventory is solid at 82.1% — always verify the vehicle history report.
• Price trend: Prices have softened 9.52% compared with last year.
• Owners rate it 4.7/5 — a strong satisfaction signal.
• The 2021 model emphasizes comfort, spacious seating, and multiple powertrain options.

Consider the 2022 if:

• At $45,826, the 2022 costs less than the current year's $46,108 average.
• Mercedes narrowed the lineup to the base six-cylinder GLS 450 4Matic.

The bottom line: If you want the broader 2021 lineup and a strong mix of luxury, space, and powertrain choice, the 2021 is the better fit. If you are price-sensitive and want the lower average cost, the 2022 is worth a look, especially if the base six-cylinder model meets your needs.

How does the 2021 Mercedes-Benz GLS compare to the 2021 BMW X7?

Expert Pros & Cons (per CarGurus review team)

2021 Mercedes-Benz GLS:

• Pros: Multiple powertrain options, Plenty of cargo space, Impressive technology.
• Cons: Cramped third row, Unintuitive technology, Poor fuel economy.

2021 BMW X7:

• Pros: Multiple powertrain options, Great handling, Powerful engine.
• Cons: Advanced safety features are not standard.

Our experts score the 2021 Mercedes-Benz GLS 8.3/10 and the 2021 BMW X7 7.7/10. The GLS looks like the better pick if you want more cargo space and a more tech-forward luxury feel. The X7 has the edge if you care more about handling and a stronger-feeling engine. Both offer multiple powertrain options, but the GLS’s drawbacks are more about usability and efficiency, while the X7’s main downside is that advanced safety features are not standard.

Read our full side-by-side expert comparison here.

These recommendations are based on CarGurus' proprietary market data from November 3, 2026, CarGurus experts' opinions, and generative AI.