Used 2021 Mercedes-Benz GLS for Sale near Colorado

How much does the 2021 Mercedes-Benz GLS cost?

Prices have softened 9.84% compared to this time last year, making it a favorable time to shop this model year.

There are 836 listings available, which gives you a decent amount of inventory to compare.

Is the 2021 Mercedes-Benz GLS a good car?

Yes — the 4.67/5 user rating points to strong owner satisfaction, and the expert rating is 8.33/10. The model scores 9/10 across Look and feel, Performance, Technology, and Safety.

The 2021 GLS is aimed at you if you want a full-size luxury SUV with three rows, a high-end cabin, and strong available performance. The overview and test-drive notes emphasize its S-Class-like refinement, spacious seating, and useful cargo flexibility, so it fits well if you want luxury utility rather than a stripped-down family hauler.

The trade-offs are real: the third row is cramped, the technology can be unintuitive, and fuel economy is poor. Even so, the GLS still stands out if you value comfort, capability, and premium presentation over efficiency.

36.6% of listings are priced as good or great deals, which suggests there are still some attractive opportunities in the market.

Is the 2021 Mercedes-Benz GLS reliable?

Owners rate it 4.67/5, a strong signal of long-term satisfaction.

The GLS is presented as a polished, comfort-first luxury SUV, and the expert notes reinforce that it delivers a composed ride and a high level of refinement. Its performance content also points to a sophisticated setup with EQ Boost support across the lineup, which helps the powertrains feel more responsive when needed.

The cost-effectiveness notes show that the six-cylinder GLS 450 is the most efficient version, while the V8-powered variants use more fuel. That means long-term ownership risk is less about basic capability and more about the costs that come with a large, complex luxury SUV.

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

Accident-free inventory is solid at 85.8% — 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 electronics, suspension behavior, and interior condition, since this is a technology-heavy luxury SUV. Pay close attention to the third row and cargo-area wear if you plan to use it as a family hauler.

Key things to evaluate:

• Trim level: The GLS is available in three levels: GLS 450, GLS 580, and Mercedes-AMG GLS 63. 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 plus 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 cabin. The GLS 450 is the best-value starting point if you want the core luxury experience without stepping too far up the price ladder.
• 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 support, which can add extra power when needed and helps the turbochargers spool more quickly.
• 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. You should check whether the specific trim you’re considering has the driver-assistance features you want, since some are optional rather than standard.
• Infotainment: The GLS uses the MBUX system with a massive touchscreen, a trackpad controller, Apple CarPlay, Android Auto, and voice control through “Mercedes” or “Hey Mercedes.” The display setup is impressive, but it can take time to learn, so make sure you’re comfortable with the interface during a test drive.
• Fuel efficiency: The six-cylinder GLS 450 returns 20 mpg city, 24 highway, 21 combined. The GLS 63 returns 14 mpg city, 18 highway, 16 combined. In combined driving, the test vehicle averaged 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, strong standard tech, and the full-size three-row format, plus the Burmester audio system and wireless charging. It makes the most sense for buyers who want the GLS’s comfort and space without paying for V8 power.
• GLS 580: This is the step-up choice if you want more power and more comfort features. The V8, heated-and-cooled front seats, massaging front seats, illuminated running boards, soft-close doors, and five-zone climate control make it feel more upscale. It suits you if you want a richer daily-driving experience and are willing to pay for it.
• Mercedes-AMG GLS 63: This is the performance-focused model, with the most powerful engine, more aggressive styling, and a sportier cabin. It is the right pick if you want the quickest and most dramatic GLS, not just the most luxurious one.

The GLS comes standard with a full suite of driver-assistance features, while additional safety tech is available on higher or better-equipped versions.

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

This looks like a moderate market for selective buyers, with enough inventory to shop carefully and enough deal activity to find value.

• Deal availability: 36.6% of listings are priced as good or great deals.
• Inventory: There are 836 listings available.
• Price trend: Prices have softened 9.84% compared with last year.
• Clean inventory: 85.8% of listings are accident-free.

If you find a listing below $46,074, 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 $46,327 sits slightly below last year's $51,382.

That decline suggests the market has moved in your favor as a buyer, but it also means a future seller may face softer pricing than owners saw a year ago. If you buy at the right number now, you may reduce the risk of taking a bigger depreciation hit later.

The GLS still has the kind of appeal that can support demand over time: it is a flagship-style luxury SUV with strong brand recognition, three-row utility, and broad premium appeal. 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 GLS earns a 9/10 safety score from our experts.

It comes standard with 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 means you get a strong standard safety foundation, but you should still confirm which driver-assistance features are included on the exact vehicle you’re considering. If you want the most advanced cruise and lane-support tech, check the option content carefully.

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:

• 36.6% of listings are priced as good or great deals.
• Accident-free inventory is solid at 85.8% — always verify the vehicle history report.
• Price trend: Prices have softened 9.84% compared with last year.
• Owners rate it 4.67/5 — a strong satisfaction signal.
• The 2021 GLS delivers S-Class-style refinement in a three-row SUV with strong available performance.

Consider the 2022 if:

• At $46,500, the 2022 costs more than the current year's $46,327 average.
• Mercedes simplified the lineup by dropping most V8 models.

The bottom line: If you want the broader 2021 lineup, stronger deal potential, and a lower average price, the 2021 is the better buy. If you prefer a newer model year and are comfortable with a simpler trim strategy, the 2022 is worth a look, but price-sensitive buyers should start with the 2021.

These recommendations are based on CarGurus' proprietary market data from October 13, 2026, CarGurus experts' opinions, and generative AI.