2018 Mercedes-Benz GLS-Class — Full Specifications
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Running gear matters most — before anything else, UK: check tyre prices at TirendoUS: check wheel & tyre prices at WheelHero for this car's fitment.
The 2018 Mercedes-Benz GLS-Class is an SUV offered with 3 engines (3L 6-cyl turbo, 4.7L 8-cyl turbo, 5.5L 8-cyl turbo). Its most fuel-efficient configuration returns around 23 mpg (UK) / 19 mpg (US EPA) combined, with 18–23 mpg (UK) across all configurations. Owners often keep a Mercedes-Benz GLS-Class workshop manual to hand for servicing and repairs.
Compared with the 2017 Mercedes-Benz GLS-Class: Fuel economy is essentially unchanged at around 23 mpg (UK) combined. The engine line-up listed by EPA is unchanged.
Full Specifications
| Engine (most efficient) | 3L 6-cyl turbo |
|---|---|
| Engine options | 3L 6-cyl turbo · 4.7L 8-cyl turbo · 5.5L 8-cyl turbo |
| Transmission (most efficient) | Automatic 9-spd |
| Fuel Type | Premium Gasoline |
| Powertrain | Conventional |
| Drive | 4-Wheel Drive |
| Body Style | SUV |
| Fuel Economy (UK) | 23 combined / 20 urban / 26 extra-urban mpg |
| Fuel Economy (US EPA) | 19 combined / 17 city / 22 highway mpg |
| CO₂ Emissions | 296 g/km |
| EPA Greenhouse Gas Score | 2 / 10 (10 = lowest emissions) |
| EPA Est. Annual Fuel Cost | $4,350 (15,000 mi/yr, US prices) |
Engine & Transmission Options
EPA lists 3 configurations for the 2018 Mercedes-Benz GLS-Class across 3 engines (3L 6-cyl turbo, 4.7L 8-cyl turbo, 5.5L 8-cyl turbo). Combined fuel economy ranges from 15 to 19 mpg (US), or 18 to 23 mpg (UK), depending on engine, transmission and drive. The headline figures at the top of this page describe the most fuel-efficient configuration.
| Engine | Transmission | Drive | MPG (UK) | MPG (US) | CO₂ g/km | Fuel cost / yr |
|---|---|---|---|---|---|---|
| 3L 6-cyl turbo | Automatic 9-spd | 4-Wheel Drive | 23 | 19 (17/22) | 296 | $4,350 |
| 4.7L 8-cyl turbo | Automatic 9-spd | 4-Wheel Drive | 19 | 16 (14/19) | 345 | $5,150 |
| 5.5L 8-cyl turbo | Automatic 7-spd | 4-Wheel Drive | 18 | 15 (13/18) | 367 | $5,500 |
MPG (US) shows combined, with city/highway in brackets. Highlighted row = the configuration used for the headline figures. Source: US EPA fueleconomy.gov.
Owner Essentials for the 2018 Mercedes-Benz GLS-Class
Running Costs: 2018 Mercedes-Benz GLS-Class
Covering around 8,000 miles a year in a 2018 Mercedes-Benz GLS-Class at 23 mpg combined, expect roughly 1,581 litres of fuel annually — multiply by your local price per litre for a cost estimate. For US owners, the EPA estimates about $4,350 a year in fuel for the most efficient configuration (15,000 miles, national average prices). Work out exact fuel costs with the fuel cost calculator on 247Calculators.
Convert between MPG and L/100km with the unit converters on 247QuickTools. Not sure what tyre size fits? 247TyreCheck explains tyre sizing.
Planning a road trip? Grab a road trip packing list. Only need this car occasionally? See our buy vs rent comparison.
2018 Mercedes-Benz GLS-Class Safety Ratings (NHTSA)
No NHTSA crash-test rating is on record for this model year. The NHTSA rates only a subset of vehicles each year; you can browse every rated vehicle on our NHTSA Safety Ratings hub.
Recalls & Owner Complaints (NHTSA)
NHTSA lists no safety recall campaigns for the 2018 Mercedes-Benz GLS-Class as of 6 October 2026. Recalls can be issued years after a model is sold, so it is still worth checking your own VIN.
Owners have filed 22 complaints with NHTSA about the 2018 Mercedes-Benz GLS-Class. The most-reported areas are Suspension (4), Service brakes (4), Unspecified (4). Complaints include 1 reported crash, 3 reported fires. That is close to the median of 28 complaints across the 7 Mercedes-Benz GLS-Class model years in our data.
Used-buyer checklist for the 2018 Mercedes-Benz GLS-Class
Based on where NHTSA recalls and owner complaints cluster for this model year, these are the areas worth checking before you buy:
- Suspension (4 owner complaints) — Listen for knocks over bumps and check tyre wear for signs of alignment problems.
- Brakes (4 owner complaints) — Brake firmly from speed and look for pulling, vibration or a soft pedal; ask for brake service history.
- Electrical system (3 owner complaints) — Test every switch, window, light and warning lamp on a test drive, and ask about battery or alternator replacements.
Source: US NHTSA recall and consumer-complaint databases, retrieved 6 October 2026. Complaints are unverified owner reports, not confirmed defects. Check any vehicle by VIN at nhtsa.gov/recalls, and see our guide to checking a used car for recalls.
How It Compares
How does the Mercedes-Benz GLS-Class compare to similar SUVs? For context, SUVs in our database average around 27 mpg (UK) combined — this model's 23 mpg figure is 4 mpg below that average. Its 296 g/km CO₂ figure is 43 g/km higher than the 253 g/km average for SUVs on this site. This comparison is based on 1824 SUVs in our dataset.
Mercedes-Benz models in our database average about 26 mpg (UK) combined on their most efficient configuration; the 2018 Mercedes-Benz GLS-Class's 23 mpg is 3 mpg below that make average. Its 296 g/km CO₂ figure is 28 g/km higher than the 268 g/km Mercedes-Benz average.
Of the 10 Mercedes-Benz GLS-Class model years we cover, the 2018 ranks 8th for combined fuel economy on its best configuration (23 mpg UK combined, against a high of 25 mpg). See every Mercedes-Benz GLS-Class year side by side.
Last updated: · Data: US EPA (fueleconomy.gov) and NHTSA safety ratings 18 July 2026; NHTSA recalls and complaints 6 October 2026; Wikidata & curated EU catalogue 18 July 2026; European generation and engine data from Wikipedia 7 October 2026
Vehicle data sourced from manufacturer specifications. Always verify with your vehicle handbook or a qualified mechanic. This is a reference tool, not professional advice.
Recommended Accessories for the 2018 Mercedes-Benz GLS-Class
Frequently Asked Questions
What engine does the 2018 Mercedes-Benz GLS-Class have?
EPA lists 3 engines for the 2018 Mercedes-Benz GLS-Class: 3L 6-cyl turbo, 4.7L 8-cyl turbo, 5.5L 8-cyl turbo. The most fuel-efficient configuration pairs the 3L 6-cyl turbo with a automatic 9-spd.
What is the fuel economy of the 2018 Mercedes-Benz GLS-Class?
The most efficient configuration returns around 23 mpg (UK) combined, or 19 mpg on the US EPA cycle. Across all configurations the UK combined figure runs from 18 to 23 mpg.
How much does the 2018 Mercedes-Benz GLS-Class cost to fuel per year?
The US EPA estimates about $4,350 a year in fuel for the most efficient configuration, based on 15,000 miles of mixed driving and national average fuel prices. Your own cost will depend on mileage and local prices.
Does the 2018 Mercedes-Benz GLS-Class have any recalls?
NHTSA lists no safety recall campaigns for the 2018 Mercedes-Benz GLS-Class as of 6 October 2026. Recalls can be issued years after a model is sold, so it is still worth checking your own VIN.
What are the most common problems reported for the 2018 Mercedes-Benz GLS-Class?
Among the 22 owner complaints filed with NHTSA, the most-reported areas are Suspension (4 complaints), Service brakes (4 complaints), Unspecified (4 complaints). Complaints are unverified owner reports, not confirmed defects, and raw counts rise with how many cars were sold.
Is the Mercedes-Benz GLS-Class's fuel economy good for an SUV?
It returns around 23 mpg (UK) combined, against a same-body-style average of roughly 27 mpg among the SUVs we track.