Mercedes-Benz ML / GLE W166 — The Good, The Bad & The Ugly

The Mercedes-Benz W166 ML / GLE is one of the more successful luxury SUVs produced by Mercedes-Benz in the modern era. Built from 2012 through to 2018, the model originally launched as the ML-Class before receiving a mid-cycle update in 2015 that introduced the GLE name as part of Mercedes’ revised SUV naming structure.

Despite the badge change, the facelifted GLE is fundamentally the same vehicle as the earlier ML. The update introduced minor styling revisions, updated infotainment, additional emissions systems, the 9-speed automatic transmission, and the plug-in hybrid variant.

From a workshop perspective, the W166 stands out as one of the most reliable luxury SUVs in its segment — particularly when compared with vehicles like the BMW X5, Audi Q7 and Volkswagen Touareg / Porsche Cayenne of the same era.

The Good — What Makes It Great

Reliable Engines & Gearboxes

From the ML250 diesel through to the AMG 63 models, we generally do not see many catastrophic failures with these engines when properly serviced. The diesel engines are economical and well suited to Australian conditions, while the petrol engines provide strong performance without excessive reliability concerns.

Wide Engine Range

One of the major strengths of the W166 platform is the variety of engines available. Buyers could choose from:

• 4-cylinder diesel (ML250 / GLE250d)
• V6 diesel (ML350 / GLE350d)
• V6 petrol options
• V8 petrol models including ML500 / GLE500
• AMG 63 models with the 5.5L twin-turbo V8

Comfort & Space

The ML / GLE is a very comfortable and practical family-sized SUV. It offers excellent ride quality, a spacious interior and good ground clearance, making it well suited to Australian conditions.

Robust Driveline

The transfer cases, gearboxes and differentials in these vehicles are generally very strong. Failure rates are low when the vehicle is maintained correctly and four matching tyres are fitted at all times.

• The 7-speed and 9-speed automatic transmissions are both extremely reliable.
• When serviced roughly every 60,000 km, they have very low failure rates.
• Minor electrical faults that do occur are typically resolved with control unit repairs or speed sensor replacements.

Safety

The W166 has excellent safety systems for its era, with a wide range of advanced driver assistance features that were ahead of many competitors at the time.

User-Friendly Technology

Compared with newer vehicles, the technology in the W166 is relatively simple and intuitive. The systems are easy to use and generally age well. Mercedes-Benz also arguably has one of the easiest cruise control systems to operate, which many owners appreciate on long drives.

The Bad — Known Weak Points

Airmatic Suspension Issues

As these vehicles reach around the 10-year mark, failures of the Airmatic air suspension system are becoming more common. Front and rear air struts, compressors and associated components can reach the end of their service life, leading to expensive repairs.

Oil Leaks

Oil leaks are common across the engine range including the 250, 350, 450, 500 and 63 models. Repair costs vary depending on the source of the leak.

The most common issue on the ML350 / GLE350d is the oil cooler leak located in the valley of the engine, which is a significant labour-intensive repair.

Early ML350 Bluetec Oil Pickup Issues

Some early ML350 Bluetec models experienced problems with the oil pickup system, which in some cases could lead to engine seizure if not addressed.

Diesel Emissions System Faults

Early diesel models can experience issues with emissions-related components including:

• NOx sensors
• AdBlue systems
• EGR components

Many of these issues are related to driving style, particularly vehicles used mainly for short trips. However, it is not uncommon for these systems to require significant maintenance between 120,000 km and 180,000 km.

M276 Timing Chain Faults

Vehicles equipped with the M276 petrol engine (such as the GLE450) can develop timing chain and camshaft adjuster issues, which can become expensive repairs if ignored.

Power Tailgate Strut Failure

A relatively common issue is failure of the power tailgate struts, which can prevent the boot from opening or closing correctly.

Handling

While the W166 is extremely comfortable, the suspension is tuned more for durability and ride comfort than sporty handling. If you want a large family SUV that also drives like a sports car, you may prefer something like the Porsche Cayenne or the right BMW X5.

The Ugly — What Can Bite You

ML63 Ownership Past 100,000 km

Once the ML63 passes around 100,000 km, plastic components in the cooling and lubrication systems can begin to fail. These issues can lead to very expensive repairs if several components fail at once.

Engine Mount Replacement

Engine mounts are another costly repair on these vehicles. Due to the design of the W166 platform, replacing them can require over 15 hours of labour in some cases. Depending on driving style, mounts may require replacement roughly every 100,000 km.

Final Thoughts

• The W166 ML / GLE is one of the most reliable luxury SUVs produced during this period.
• Engines and driveline components are generally very robust.
• The vehicle offers excellent comfort, practicality and long-distance usability.
• However, like any European luxury vehicle, proper maintenance is essential.
• These vehicles can last a long time when maintained correctly, but owners should be prepared for ongoing investment in maintenance and repairs to ensure long-term reliability.
• Compared with rivals such as the X5, Q7 and Touareg / Cayenne, the W166 often proves to be one of the strongest options in the segment from a reliability standpoint.