Models · Mercedes-Benz
Mercedes-Benz GL / GLS X166 buying guide
The second GL, a seven-seat luxury SUV sold from 2012 and renamed GLS with a 2016 facelift. Almost all UK cars are the 3.0 V6 diesel, problems are relatively rare, and owners are generally satisfied.
The versions
- GL350 BlueTEC: 3.0 V6 diesel, 258bhp, with the seven-speed 7G-Tronic Plus automatic
- GLS 350d from 2016: 3.0 diesel with the smoother nine-speed 9G-Tronic automatic
- Permanent 4Matic four-wheel drive; optional Off Road package with low range and a centre differential lock
- Air suspension, with Active Curve Control on some cars
- The GL63 and GLS 63 AMG are covered separately
What to check on a X166 GL / GLS
3 model-specific things to look at when you view one. They're a starting point, not the full inspection.
Air suspension warnings
What to look for: When you arrive, check the car sits level on all four corners. Start it and watch the dashboard for a message such as "Please wait, car is rising", and listen for the compressor running for a long time.
Why it matters: A rising message at start-up may signal an air leak, which can lead to the compressor failing if it's left. Compressors, relays, hoses and valves have all failed on Airmatic-equipped Mercedes of this era, so recent suspension work on the invoices is a plus.
Electrics and air conditioning
What to look for: Test the sat nav, every fitted extra, all seat adjustments including the powered third row if fitted, and the air conditioning front and rear. Check no warning lights stay on after start-up.
Why it matters: Electrical issues and interior trim were the problems owners reported most often on this generation. They're complicated cars, so confirming everything works is the best check you can do at the viewing.
The panoramic roof
What to look for: If a panoramic roof is fitted, open and close the blind and the glass fully, and listen for creaks or grinding. Look at the headlining around it for water stains.
Why it matters: Some problems were reported with the optional panoramic roof on this generation. A roof that opens, closes and seals properly is what you want to see.
Also in the full guide
- Underside damage
- The cold start, test drive and paperwork checks for the exact version you're viewing
The full guide to the X166 GL / GLS
The CrankSight guide walks you round the car on your phone at the viewing, with every check for the exact version you're looking at: what to look for, where to find it, and what anything you find is likely to cost. As you go it builds an assessment of that car, and if you view more than one, it lines them up side by side.
£29 for the model, used on as many cars as you like, delivered within 72 hours or your money back.
Other generations
General points for the model, last checked October 2026. Every car is different, so treat this as a guide to what to look at, not a verdict on any car. CrankSight is independent and has no connection with Mercedes-Benz.