Used 2021 Mercedes-Benz GLS for Sale nearPhiladelphia, PA

How much does the 2021 Mercedes-Benz GLS cost?

Prices have softened 10.78% compared to this time last year, making it a favorable time to shop this model year.

There are 831 listings available, which suggests solid inventory for shoppers comparing prices and trims.

Is the 2021 Mercedes-Benz GLS a good car?

Yes — the 2021 Mercedes-Benz GLS earns a 4.7/5 user rating and an 8.3/10 expert rating. The model scores 9/10 across Look and feel, Performance, Technology, and Safety.

It fits your needs best if you want a luxury-first full-size SUV with three rows of seating, a spacious cabin, and enough cargo room for family duty and larger hauls. The GLS also stands out for its upscale presentation and strong technology, which supports its flagship-SUV mission.

The main trade-offs are a cramped third row and unintuitive technology, along with poor fuel economy. If you value comfort, space, and premium features more than efficiency, those compromises may be easy to live with.

39.5% of listings are priced as good or great deals, which gives you some room to shop selectively.

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 usability, and its expert review emphasizes a composed, luxury-focused driving experience. It also pairs that with multiple powertrain choices and a well-equipped cabin, which can help support confidence over time if the vehicle has been maintained properly.

Its performance content points to strong output across the lineup, and the mild-hybrid system is designed to add extra power when needed. That kind of engineering can be a plus for refinement, but it also makes a careful service history especially important on a used example.

If you buy one, prioritize maintenance records and a thorough pre-purchase inspection so you can reduce the risk of expensive ownership surprises.

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 report carefully, even when the market looks clean overall. A pre-purchase inspection should focus on the cabin electronics, suspension behavior, and any signs of uneven wear, since this is a complex luxury SUV. Pay close attention to how the vehicle drives at low speeds and over rough pavement, because comfort and refinement are central to the GLS experience.

Key things to evaluate:

• Trim level: 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 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, a quad-outlet exhaust, a chrome slotted grille, and a performance-inspired steering wheel.
• 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 EQ Boost 48-volt mild-hybrid assistance.
• Safety package: Standard 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 through “Mercedes” or “Hey Mercedes.” The digital dash is also controlled through touch-sensitive steering-wheel pads.
• Fuel efficiency: The GLS 450 returns 20 mpg city, 24 highway, 21 combined. The GLS 63 returns 14 mpg city, 18 highway, 16 combined. In weeklong mixed driving, the observed average was 15.3 mpg.

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 best-value choice if you want the GLS experience with the broadest mix of standard equipment, including heated front seats, wireless charging, Apple CarPlay, Android Auto, and the Burmester audio system. It gives you the core luxury and tech without stepping into the much pricier V8 models.
• GLS 580: Choose this if you want more power and more comfort features, including heated-and-cooled front seats, massaging front seats, soft-close doors, and five-zone climate control. It suits you best if you want a more indulgent daily driver and are willing to pay for it.
• Mercedes-AMG GLS 63: This is the performance-focused choice, with the most powerful engine, more aggressive styling, and a sportier cabin presentation. It makes sense if you want the quickest and most dramatic GLS, not the most practical one.

Safety equipment is strong across the lineup, with standard driver-assistance features and additional available aids on higher-spec versions.

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

This looks like a moderate, selective buyer’s market, so you can shop carefully without rushing.

• Deal availability: 39.5% of listings are priced as good or great deals.
• Inventory: There are 831 listings available.
• Price trend: Prices have softened 10.78% compared with last year.
• Clean inventory: 82.1% of listings are accident-free.

If you find a listing below $45,367, 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 $45,367 sits slightly below last year's $50,851.

That price movement suggests the market has already adjusted downward, which can help you buy at a more favorable point in the cycle. For a future seller, that means resale value will depend heavily on condition, mileage, and how well the vehicle has been maintained.

Because the GLS is a luxury SUV with strong equipment and broad appeal, a clean example should still attract interest from shoppers who want space and premium features. If you keep it in excellent condition, you improve your odds of holding value better than a neglected example would.

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 2021 Mercedes-Benz GLS earns a 9/10 safety score from our experts.

The GLS 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. It also offers lane-keep assist, lane-change assist, adaptive cruise control, a following-distance indicator, and stop-and-go cruise control.

That gives you a strong standard safety foundation, with additional driver-assistance features available if you want more support on the road. The main caveat is that some of the more advanced aids are optional rather than standard.

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:

• 39.5% 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 10.78% 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 $45,466, the 2022 costs more than the current year's $45,367 average.
• Mercedes made the base six-cylinder the only available version at the time.

The bottom line: If you want the broader trim and powertrain range, the 2021 is the better target. If you’re price-sensitive and mainly want the GLS’s luxury-first space and comfort, the 2021 also looks attractive because prices have eased and inventory is healthy.

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 leans harder into luxury comfort, cargo space, and technology, while the X7 emphasizes handling and a powerful engine. If you want the more comfort-focused full-size SUV, the GLS has the edge; if you care more about driving feel, the X7 is the stronger fit.

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

These recommendations are based on CarGurus' proprietary market data from November 10, 2026, CarGurus experts' opinions, and generative AI.