Buying a used Mercedes is a calculated risk. Done right, you save 30–50% versus a new car and end up with a vehicle that's still a Mercedes. Done wrong, you inherit someone else's $12,000 transmission problem. Here's the 12-point checklist we use during a paid pre-purchase inspection, in plain English, so you can do a first-pass walk-around before paying us for the full job.
## Before you turn up — five-minute desk check
Before you even open the door, run two checks online:
1. REVS / PPSR — at ppsr.gov.au, $2 search. Tells you if the car is financed, written off, or stolen. If anything shows up, walk away. 2. VIN decode — vin-info.com or similar. Confirms the model, build year, factory options. If the seller's listing says "AMG" and the VIN decodes to a base C200, walk away.
If both come back clean, take the car for the test drive.
## The 12-point walk-around
### 1. Service history paperwork — the most important single thing
The Mercedes Digital Service Book (DSB) is the official record of every authorised service. Any independent specialist worth their salt — including us — writes to the DSB through XENTRY when they service a car.
Ask the seller for:
- The physical logbook with stamps for every service - A printout of the DSB record (the dealer or any independent specialist can pull this) - Receipts for any major work done outside scheduled servicing
Red flags: gaps of more than 18 months between services, missing stamps, "lost the logbook", or only dealer-stamped services with no detail of what was done.
### 2. The cold start
Get to the car before the seller does, and put your hand on the bonnet. If it's warm, they've pre-started it to mask a cold-start rattle. Walk around the back of the car and ask them to start it from cold — listen for:
- Rattle for more than 2 seconds at startup — VVT actuator or chain tensioner, ~$2,400 fix on M276 V6 - Diesel knock that doesn't smooth out within 30 seconds — injector or glow plug issue, ~$1,200–$2,800 - Blue smoke at startup — valve-stem seals, common on high-km M276, ~$2,200 fix - Fuel smell strong enough to notice from outside the car — fuel-rail or injector leak
### 3. The 9G-Tronic (or 7G-Tronic) test
Drive the car slowly through 1st to 4th gear, then accelerate moderately to climb to 6th or 7th. Listen and feel for:
- Flare or slip between gears — transmission fluid out of spec or worse - Hard 2-3 upshift under light throttle — common 722.9 7G-Tronic complaint, conductor plate fix ~$1,600 - Reverse engagement clunk that takes more than half a second — torque converter wearing
If the transmission has any of these symptoms and the seller hasn't disclosed it, walk.
### 4. Brake test on a quiet straight
Find an empty stretch of road, get to 80 km/h, and brake firmly (not panic-stop). You're listening / feeling for:
- Vibration through the pedal or steering — warped rotors, $720–$980 fix - Pull to one side — caliper sticking, $480–$680 per side - Spongy pedal — air in system, $145 flush minimum - Squealing — pads at the wear indicator, $480–$680 fix
Mercedes brake systems are durable but not bulletproof; a car with 80,000+ km that's never had a brake refresh is due for one.
### 5. Body and panel fit
Walk around the car and check the panel gaps. Mercedes ship from the factory with gaps you could lay a 4 mm gauge into and have them all equal. If one panel sits higher than the next, or the gap is wider on one side of the boot than the other, that panel has been re-fitted after a collision.
Also check:
- Paint mismatch under different lighting — sun, shade, garage - Overspray in door jambs or wheel wells - Fresh undercoating on a 5+ year old car — usually hides repair work - Headlight clarity — if both headlights are foggy, age. If only one is clear, recent replacement after collision.
### 6. Tyre wear
Tyres are honest. Check all four for:
- Inner-edge wear — alignment issue, $185 to fix the alignment - Outer-edge wear — toe out of spec or worn bushings - Cupping or scalloping — worn shock absorbers, $640 per pair - Mismatched brands or sizes — either careless owner or hiding a wheel-specific problem
Aged tyres (date code more than 5 years old) need replacing regardless of tread depth. The DOT code is moulded into the sidewall.
### 7. Interior wear vs odometer
A car that's done 60,000 km should have:
- Steering wheel leather that's still tight (not shiny on the grip) - Driver's seat bolster intact (not collapsed) - Pedal rubber present (not worn to the metal) - Driver's door card unblemished where the door check arm rests
If the interior wear doesn't match the odometer, the odometer's been wound back. Walk.
### 8. Electronics check
Sit in the car and run through:
- All four windows — fully up, fully down, one-touch behaviour - All four door locks - Climate control — both zones if dual-zone, hot and cold both directions - Infotainment — full reboot from off, all menus respond - Reverse camera — clear image, no horizontal lines - All warning lights extinguish within 3 seconds of starting
### 9. Underneath — pop the hood
You don't need to know what every component is. You need to look for:
- Oil on the engine block — leak, severity depends on where - Coolant in the overflow tank at the correct level - Air filter clean (lift the housing if you can) - No aftermarket wiring spliced into the loom
Walk to the rear of the car and check the exhaust:
- Soot at the tailpipe — normal on diesels, concerning amount on petrols - Wetness inside the tailpipe — oil burn
### 10. The OBD-II quick check
If you've got a basic OBD reader, plug it in and pull codes. Anything other than "no codes stored" deserves an explanation from the seller. Even cleared codes leave a "readiness monitor incomplete" status — if all monitors say "not ready" on a car that's just been driven, the codes were cleared in the last 50 km. That's deliberate.
### 11. Tow and bumper inspection
Walk to the rear of the car, kneel down, and look behind the bumper at the tow-eye attachment point and the boot floor. Collision repairs leave evidence here — bent metal, fresh paint, mis-aligned panels — that's invisible from above.
### 12. The deal-breaker question
Ask the seller: "Has this car ever been in an accident?" Watch their face. If they hesitate, it has been. If they immediately say "no, never", check the panel gaps and underside again.
## When to walk
Any single one of these isn't necessarily fatal, but if the car shows three or more of:
- Service gaps over 18 months - Cold-start rattle for more than 2 seconds - Transmission flare or hard shifts - Panel-gap mismatch + paint mismatch - Interior wear inconsistent with odometer - Aftermarket wiring under the bonnet
…the price needs to drop substantially or you walk. There's another Mercedes for sale next week.
## When to book a proper PPI
If the car passes your walk-around, the next step is a proper [pre-purchase inspection](/services/pre-purchase-inspection). We do 120-point inspections at the workshop for $295, or mobile inspections at the seller's location for $295 + a call-out fee depending on suburb. You get a written report with photos within 24 hours.
The math is straightforward: $295 + maybe $150 call-out = $445 to find a $9,000 transmission problem before you buy is the best money you'll spend on the deal. We've found enough hidden issues over the years that we'd rather you cancel a sale than buy a problem.
[Book a pre-purchase inspection online](/book) — choose "Pre-Purchase Inspection" in the service dropdown, enter the seller's address if mobile, and we'll confirm by SMS within an hour. See [the full PPI service page](/services/pre-purchase-inspection) for what's covered, and [our diagnostics page](/services/diagnostics) for the Xentry scan that catches what generic scanners miss.