Mercedes-AMG A45 Buying Guide: Common Problems and What to Check Before You Buy
The A45 is the hyper-hatch that took the four-cylinder somewhere no one expected: the most powerful series-production four ever built, in a five-door family body. That combination of accessibility and ferocity is exactly why so many get driven hard, all year, and modified more than almost anything else in this class. None of that is automatically a problem. Undisclosed or poorly documented, it can be an expensive one.
The single most important thing to understand before buying any A45: a car’s history is not the same as its condition, and neither is fully visible in the car advert. A folder of receipts tells you what was paid for, not what was skipped. This guide covers both generations, what tends to go wrong on each, and what a car advert won’t tell you.
At a glance: which A45 is which
| Generation | Years | Engine | Output | Drivetrain |
|---|---|---|---|---|
| W176 | 2013–2018 | M133 2.0 turbo four | ~360–381 PS (rose with the facelift) | 7-speed AMG DCT · 4MATIC · hatch |
| W177 | 2019–present | M139 2.0 turbo four (hand-built) | A45 S ~421 PS | 8-speed AMG DCT · 4MATIC+ · hatch |
The W177’s M139 is hand-built (one engine, one builder) and the A45 S adds a torque-vectoring rear axle with a drift mode. Note a UK-specific quirk: the W177 was sold here as the A45 S (421 PS) only: the lower-output 387 PS base A45 was never offered through UK dealers. So a UK-registered car logged simply as a base “A45 4MATIC+” is either a data-mapping error or a grey import worth checking. The closely-related CLA45 (four-door coupé) is the A45’s sister and is covered too: check live coverage.
Common problems by generation
W176 A45 (2013–2018)
- Early turbo service action. Early pre-facelift cars (2013–14) were subject to a Mercedes service action for contamination in the turbocharger oil feed, and the earliest turbos are more prone to wear. On an early car, check the work was done.
- Cold dual-clutch engagement. A crunch or clunk when selecting Reverse from a stone-cold start is a known trait, sometimes addressed by a software update. A brief noise isn’t necessarily trouble; persistent harshness or hesitation warrants a closer look at the gearbox.
- High-pressure fuel pump. A raw fuel smell on cold start can point to the engine-mounted high-pressure fuel pump: worth investigating, since you don’t want fuel weeping near a hot engine.
- Red paint. The non-metallic reds (Mars Red, and sometimes Jupiter Red) are prone to clear-coat bubbling and peeling. If you’re looking at a red car, check the bonnet, roof and pillars closely.
W177 A45 (2019–present)
- Exposed radiators. The front-bumper design leaves the auxiliary cooling radiators exposed to stone damage, which can cause slow, hidden coolant loss; the sensors can also throw the odd false “low coolant” warning. Check the coolers and any coolant history.
- Transmission limits and tuning. The W177’s 8-speed dual-clutch is tightly torque-limited from the factory. Cars pushed past stock power on standard transmission software can show jerky low-speed shifts, delayed reverse and clutch slip, so a tuned car needs its gearbox assessed carefully (see below).
- Electronics. Confirm the MBUX system, cameras and driver-assist features all work as they should on the test drive.
Modification and tune history: the big one for the A45
This matters more on the A45 than almost anything else in the class. The M133 and M139 hold the records for the highest specific output of any series-production four-cylinder, which means they already run close to their thermal and structural limits from the factory. Heavy ECU remapping, bypassing the transmission’s torque limits, and frequent Race Start launches all accelerate wear on the dual-clutch gearbox, the differentials and the engine mounts. Treat a heavily modified, hard-launched A45 as a car that needs much closer scrutiny than a standard, well-documented one, and a clear, evidenced account of exactly what’s been done is worth a lot.
Beyond the mechanicals: history and provenance red flags
Two cars with identical engines can be worth thousands apart on history alone. Before you focus on mechanical condition, the paper trail has to stand up:
- Service history gaps: especially around major-service intervals. Missing stamps aren’t automatically disqualifying, but they change the price.
- Mileage that doesn’t add up: MOT records should tell a consistent story year-on-year. A jump or a stall is worth understanding before you view.
- Outstanding finance: a car can’t be sold cleanly with money owed against it. This is a five-minute check that prevents a very bad day.
- Accident or write-off markers: a recorded repair isn’t always a deal-breaker, but you need to know it’s there and price accordingly.
- Specification that doesn’t match the car advert: claimed options that aren’t actually fitted are common, and on an AMG the spec drives the value.
None of these require you to be in the same room as the car. All of them are checkable in advance.
What a car advert and a test drive won’t tell you
It helps to think of an A45 purchase as three layers of truth:
- What the seller says: the car advert, the description, the conversation. Useful, but unverified.
- What the records say: MOT and mileage consistency, finance, stolen and write-off markers. This is data verification, and it can be done before you travel.
- What only a physical inspection reveals: compression and leak-down results, suspension and bushing wear, dual-clutch and all-wheel-drive driveline health, the things you can only find with the car on a ramp.
Most buyers do layer 1, skip straight to a test drive, and only reach layer 3 (a proper PPI) on the one car they’ve already half-committed to: sometimes after a long drive to see it. Doing layer 2 first is what stops you wasting a Saturday on a car whose history was never going to check out.
To be clear about the limits: data verification confirms a car is what it claims to be on paper. It does not replace a physical, mechanical pre-purchase inspection. The two do different jobs, and a careful A45 buyer does both: in that order.
How Chequered Past helps
Chequered Past is the layer-2 step. You give us the registration; we check the official records on that car: the factory spec, MOT and mileage consistency, outstanding finance, stolen and write-off markers, keepers and the value, and we’re explicit about anything we couldn’t confirm.
What it does: tells you, before you travel, whether a car is what it says it is. What it doesn’t do: replace a physical inspection of mechanical condition. We’ll always tell you where that line is.
Run a history check on an A45 you’re considering →
Frequently asked questions
Which A45 should I buy: W176 or W177? The W176 is the value buy and still seriously fast; the W177 A45 S is a big step on power, the hand-built M139 engine, and cabin tech. Whichever you choose, the individual car’s history matters more than the generation, and given how heavily these are modified, a standard, well-documented car is often worth more than a faster, mapped, mystery one.
Are used A45s reliable? Maintained properly, they’re remarkably capable everyday performance cars. The catch is that they’re highly stressed and heavily tuned as a group, so the real risk is less the model and more how this car has been serviced, modified and driven, which is exactly what a history check surfaces.
Do I need the car’s registration? Yes. The free check and the £10 vehicle history check both run on the registration.
Can you check a modified or tracked A45? Yes. We surface the signals; you decide what they mean for you. The goal is an informed decision, not a pass/fail.
Other Mercedes-AMG guides: Mercedes-AMG buying guide hub
Chequered Past is an independent analysis service and is not affiliated with, endorsed by, or connected to Mercedes-Benz Group AG, Mercedes-AMG GmbH, or any vehicle manufacturer. Data is drawn from licensed DVLA and DVSA records via our data provider.