Mercedes-AMG's front-mid-engine sports car, hand-built in Affalterbach. The M178 4.0L biturbo V8 is a fundamentally strong engine shared (in M177 form) with the C63 and E63 AMG. The dry-sump lubrication, rear-mounted transaxle, and aluminium spaceframe give it genuine supercar credentials. Most owners report reliable powertrains, but the Getrag 7-speed DCT is the car's weak point and can be devastatingly expensive to repair.
Robust hand-built M178 V8
Strong value vs Porsche/Ferrari
DCT gearbox repairs very costly
High consumable costs (tires, brakes)
Buy if: You want a front-engine V8 sports car with genuine supercar performance and can budget for premium consumables and occasional expensive repairs.
Avoid if: You cannot absorb a potential transmission bill exceeding €10,000 or want low running costs.
Expected Annual Maintenance Costs
Common Problems
Electro-hydraulic clutch control unit and internal sensors fail, requiring transaxle removal · more· less
The Getrag 7DCL750 dual-clutch transmission is the AMG GT's most expensive weak point. Failures typically manifest as harsh shifting on even-numbered gears, buzzing or grinding from the rear, and dashboard error messages including damper malfunction and differential lock warnings. The transmission may default to odd gears only (1-3-5-7) in limp mode. The root cause is often the electro-hydraulic clutch control unit or internal RPM sensors that cannot be repaired separately. Repair requires complete transaxle removal. Dealer quotes typically range from €8,000 to €12,000 for a rebuild, with full replacement reaching €15,000+. Some owners have reported going through multiple transmissions. The issue tends to appear between 40,000 and 80,000 km, though some cars reach 100,000+ km without trouble. A specialist rebuild rather than dealer replacement can save significantly.
Wastegate flapper wears and rattles at low rpm, progresses to limp mode if ignored · more· less
The turbocharger wastegate flappers develop play over time due to the constant back-and-forth movement wearing the pintle and actuator rod. This produces an audible rattle, particularly at low rpm and partial throttle. Initially it is cosmetic but can eventually cause the engine to enter limp mode. Mercedes issued a Technical Service Bulletin (LI09.40-P-061542) addressing this issue. Aftermarket stainless steel wastegate repair kits are available for around €200-400 in parts, with labor around €300-600. If the turbo internals are damaged from prolonged wastegate malfunction, full turbocharger replacement costs €2,500-3,000 per side. A software update to alter wastegate actuation timing is not available for AMG models due to different pressure and actuation conditions.
Internal separator fails, causing oil leaks and excessive crankcase pressure · more· less
The oil separator on the M178 engine can fail internally, causing crankcase pressure imbalance and oil leaks around the rear of the engine near the transmission bellhousing. Symptoms include a high-pitched squeak that disappears when the oil filler cap is removed, rough idle, and visible oil around the separator housing. The dry-sump system adds complexity to the repair. The separator itself costs €300-500, but labor is significant due to engine access constraints, bringing total repair to €800-2,000 depending on whether a specialist or dealer performs the work. Typically occurs after 50,000-80,000 km.
Electronically controlled dampers leak or lose performance, typically after 60,000-100,000 km · more· less
The AMG GT S uses electronically controlled adaptive dampers (AMG RIDE CONTROL) that adjust firmness based on the driving mode selected. These units develop oil leaks and reduced damping performance over time, typically between 60,000 and 100,000 km. Symptoms include a noticeably softer or harsher ride on one corner, visible oil weeping on the damper body, and in some cases a damper malfunction warning message. OEM replacement dampers cost approximately €600-800 per unit. With the staggered setup (different front and rear specifications), a full set replacement at a dealer runs €3,000-4,000. Specialist shops can source aftermarket equivalents like Bilstein or KW units at lower cost, reducing total repair to €1,500-2,500.
Actuator spring or motor fails, causing exhaust flap to stick open or closed · more· less
The performance exhaust system uses electrically operated flap valves that open under load for a more aggressive exhaust note. The actuator contains a coupling spring designed as a sacrificial component that breaks before the motor or flap is damaged. Once failed, the exhaust flap typically sticks in one position. Symptoms include the exhaust remaining permanently loud or quiet regardless of mode selection. Dealer replacement costs €600-1,200 per actuator including programming. Some owners opt to have the flaps welded open or removed entirely as a cheaper alternative, though this affects noise levels and may not pass inspection in some countries.
Multiple control modules maintain standby current, draining battery within 10-14 days · more· less
Like many modern Mercedes models, the AMG GT S has significant parasitic current draw from its numerous electronic control modules that remain in standby mode. The battery can drain flat within 10-14 days if the car is not driven or connected to a trickle charger. This is a characteristic of the car rather than a defect. A quality battery maintainer (CTEK MXS 5.0 or similar, approximately €80) is essential for any AMG GT that is not driven daily. If the battery is repeatedly deep-discharged, the AGM battery will need replacement at €250-500 depending on source.
Strong engine, but expensive transmission when it fails
The M178 V8 is a robust, well-engineered unit and many AMG GTs exceed 100,000 km with no major engine concerns. The primary risk is the Getrag DCT transaxle, which is expensive to repair due to the rear-mounted layout requiring complete removal for any internal work. Wastegate rattle and damper wear are the other notable concerns. Regular transmission fluid changes (despite Mercedes suggesting lifetime fill) and keeping a trickle charger connected when parked will help extend component life.
Recalls and Technical Service Bulletins
Carbon fiber driveshaft adhesive bond failure (2015-2016 production)
Critical - verify completed
Carbon fiber driveshaft flange bond insufficient (2016-2017 models)
Critical - verify completed
eCall emergency system SIM card software disabled (2017-2022 models)
OTA update or dealer - verify completed
PRE-SAFE side radar sensor software fault (2018-2019 models)
Verify completed
Contact Mercedes-Benz with the VIN to verify all recalls have been completed. The driveshaft recall is particularly important on early production cars (2015-2016) as it involves a safety-critical bonding failure.
Warranty Status
Factory warranty (2 years)
Expired on all used AMG GT S models
Mercedes extended warranty
Available through Mercedes dealers, typically €2,000-4,000/year
Rust perforation warranty (30 years)
May still apply on newer cars - verify with VIN
All used AMG GT S models are outside their original 2-year factory warranty. Extended warranty coverage is available through Mercedes-Benz dealers but typically excludes wear items and may have mileage limitations. Given the potential cost of transmission repairs, extended warranty can be worthwhile if the terms cover the DCT transaxle.
This report is for informational purposes only and does not constitute professional advice. Estimates may be inaccurate. Always have a qualified specialist inspect the vehicle before purchase. We accept no liability for decisions made based on this information.