Used 2021 Mercedes-Benz GLS for Sale nearDetroit, MI

How much does the 2021 Mercedes-Benz GLS cost?

Prices have softened 11.67% compared to this time last year, making it a favorable time to shop this model year.

There are 803 listings available, which gives you a meaningful amount of inventory to compare.

Is the 2021 Mercedes-Benz GLS a good car?

Yes — the 4.67/5 user rating and 8.33/10 expert rating both point to a strong overall showing. The 2021 Mercedes-Benz GLS is positioned as a full-size luxury SUV with three rows of spacious seating, a luxury-first cabin, and plenty of cargo space for larger loads. It also brings multiple powertrain options and impressive technology, which helps it stand out in the segment.

The trade-offs are real, though: the third row is cramped, the technology can be unintuitive, and fuel economy is poor. If you want a large SUV that prioritizes refinement, passenger comfort, and upscale presentation over simplicity or efficiency, this model year fits that use case well.

The model scores 9/10 across Look and feel, Performance, Technology, and Safety.

Cons: Cramped third row and unintuitive technology are the main compromises, and poor fuel economy may matter if you drive a lot.

Market signal: 36.2% of listings are priced as good or great deals, so you have room to shop selectively.

Is the 2021 Mercedes-Benz GLS reliable?

Owners rate it 4.67/5, a strong signal of long-term satisfaction. The GLS is built around a comfort-first, upscale formula, and the expert review emphasizes its composed ride, strong performance, and high-end fit-and-finish. It also uses Mercedes’ EQ Boost 48-volt mild-hybrid system across the engine lineup, which supports the powertrain and helps smooth operation.

The performance notes also point to a hushed, composed ride and a vehicle that drives and handles like a smaller SUV than it is. On the cost side, the GLS 450 is the most efficient variant, while the V8 models use more fuel, so ownership costs can rise quickly depending on trim and how you drive it.

For used buyers, the biggest long-term risk is that a complex luxury SUV can be expensive to keep up if you choose a higher-output version or a heavily optioned example.

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

Accident-free inventory is solid at 83.9% — always verify the vehicle history report.

You should still check the history report carefully, because a clean listing percentage does not replace a proper records review. Prioritize a pre-purchase inspection that focuses on the electronics, cabin controls, and any signs of heavy wear in the third row and cargo area. Since this is a luxury SUV with a lot of equipment, condition matters as much as mileage.

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, a quad-outlet exhaust, a chrome slotted grille, and a performance-inspired interior. The GLS 450 is the best-value starting point if you want the core luxury experience without paying for the V8 upgrades.
• 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, which can add 21 hp and 184 lb-ft when needed.
• 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. Some of those driver-assistance features are not standard.
• Infotainment: The GLS uses the MBUX infotainment system with a massive touch screen, a trackpad controller, Apple CarPlay, Android Auto, and voice control through “Mercedes” or “Hey Mercedes.” The system is designed around large, easy-to-read icons, but it can still take time to learn.
• 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 trim to start with if you want the core GLS experience at the lowest entry point. You still get the luxury basics, the MBUX system, wireless charging, Apple CarPlay, Android Auto, and a strong standard safety list, so it covers the essentials well.
• GLS 580: This is the step-up choice if you want more power and more comfort features. The V8, massaging front seats, soft-close doors, and five-zone climate control make it the more indulgent pick, but it costs more to get there.
• Mercedes-AMG GLS 63: This is the performance-focused choice. It adds the most aggressive styling and the strongest engine, so it suits you if you want the quickest and most dramatic version of the GLS rather than the best value.

Standard safety equipment is generous across the lineup, but some advanced driver-assistance features remain optional.

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

This is a moderate market for selective buyers, so you can shop carefully and still find worthwhile listings.

• Deal availability: 36.2% of listings are priced as good or great deals.
• Inventory: There are 803 listings available.
• Price trend: Prices have softened 11.67% compared with last year.
• Clean inventory: 83.9% of listings are accident-free.

If you find a listing below $46,199, 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 $46,213 sits slightly below last year's $52,319.

That decline suggests the market has already adjusted downward, which can help you as a buyer today but may limit upside if you plan to resell soon. For a future seller, the key takeaway is that pricing momentum has softened, so condition, mileage, and trim choice will matter even more when it is time to list the vehicle. Well-kept examples with desirable equipment should hold up better than average ones.

Vehicles with strong owner satisfaction ratings, like this model year's 4.67/5, 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.

Standard driver-assistance equipment includes Active Brake Assist, forward-collision avoidance, blind-spot monitoring, automatic high beams, automatic parking assist, a surround-view camera system, a driver-drowsiness monitor, and crosswind assist. Available upgrades include lane-keep assist, lane-change assist, adaptive cruise control, a following-distance indicator, and stop-and-go cruise control.

That gives you a strong safety foundation, but some of the more advanced convenience features are still 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:

• 36.2% of listings are priced as good or great deals.
• Accident-free inventory is solid at 83.9% — always verify the vehicle history report.
• Price trend: Prices have softened 11.67% compared with last year.
• Owners rate it 4.67/5 — a strong satisfaction signal.
• The 2021 model combines multiple powertrain choices with a luxury-first cabin and strong standard tech.

Consider the 2022 if:

• At $46,871, the 2022 costs more than the current year's $46,213 average.
• Mercedes withdrew most V8 models, leaving only the base six-cylinder GLS 450 4Matic.

The bottom line: If you want the broader trim and powertrain range, the 2021 is the better target because it gives you more choices at a lower average price. If you are price-sensitive and only want the base six-cylinder setup, the 2022 can make sense, but you will likely pay more for a narrower lineup.

These recommendations are based on CarGurus' proprietary market data from September 29, 2026, CarGurus experts' opinions, and generative AI.