Inspecting a used car before you buy it is not about proving the car is "perfect." It is about uncovering problems that affect safety, the validity of ownership, the car's value, and the cost of repairs after purchase.
Start with an initial inspection on your own to decide whether the car is worth moving to the next stage. But don't treat a do-it-yourself checklist as a substitute for a professional inspection, because assessing the chassis from underneath, measuring paint thickness, reading the control modules, testing engine compression, and checking the transmission may require a lift, diagnostic equipment, and technical expertise.
The decision rule:
A car doesn't pass inspection just by the number of items that check out. A single problem with the chassis number, the structural body, the airbags, or engine overheating can matter more than 20 cosmetic items in good condition.
The checklist is divided into seven groups:
| Group | Number of points | What are you trying to uncover? |
|---|---|---|
| Identity and paperwork | 4 | An ownership or data problem, or a sale ban |
| Body and paint | 6 | A previous accident or structural repair |
| Tires, brakes and suspension | 4 | Safety risks and upcoming expenses |
| Engine and fluids | 5 | Leaks, wear or overheating |
| Transmission and drivetrain | 3 | Jerking, delays or slipping |
| Cabin and electronics | 4 | Odometer tampering or safety faults |
| Test drive | 4 | Problems that don't show up while stationary |
| Total | 30 | A purchase decision based on the car's actual condition |
Don't set out for a viewing before you know whether the car is worth your time.
Ask the seller about:
Ask for clear photos of the car from every angle, plus a photo of the odometer, the trunk floor and the engine bay. You can also ask for a video of the engine being started cold, but a video is no substitute for starting it in front of you or having it professionally inspected.
A seller who refuses to allow an independent inspection, pressures you to pay a deposit before you have seen the papers, or whose legal capacity to sell is unclear—each of these is reason enough to pause the deal until the information is clear. Conservative inspection checklists treat a refusal of a professional inspection, or any discrepancy in the car's details, as a red flag rather than just a negotiating point.
Natural light helps you see:
Avoid inspecting at night or in the rain, as poor lighting and water can hide paint differences and body defects.
Starting the engine from cold can reveal:
If the engine is already warm when you arrive, ask why, and don't take a smooth start as sufficient proof that it is healthy.
You may need:
Don't use any tool or test that could damage the paint or electrical systems, and don't rely on a magnet alone to judge whether there is body filler, because some parts of modern cars are made of aluminum or plastic.
The inspection should start with the car's legal identity, not the sound of the engine. A car can be mechanically sound and the deal can still fall through because of mismatched numbers or a seller who lacks the legal capacity to sell.
Ask to see:
Verify whether the person who will receive the money and sign the contract is the registered owner, or holds a document that authorizes them to sell.
"The car belongs to someone I know" is not enough. If the sale is being made under a power of attorney, you must review the original power of attorney, its powers, and the chain of any previous powers of attorney, if there are any.
Classification: Critical
Decision if it fails: Stop the deal until official verification.
Compare the chassis number (VIN) on the car with the number recorded on the registration license or the vehicle data certificate.
Inspect where the number is located for signs of:
Any discrepancy or possible tampering with the chassis number is not a defect that can be resolved with a price discount. The deal must be stopped and the number verified with the competent authority.
Classification: Critical
Decision if it fails: Walk away or pause the deal pending official verification.
Verify that the following match:
Replacing the engine can be legitimate if the proper procedures were completed, but the correct details must be reflected in the accepted documents.
Classification: Critical
Decision if it fails: Don't pay until the details are corrected and verified.
Check:
Don't assume that a valid license automatically means the car is free of all restrictions. And don't treat an online check on its own as a substitute for the official procedures.
Classification: Critical
Decision if it fails: Hold off on the deposit and payment until the restriction is lifted.
The goal here is not just to find any repainted part, but to determine the reason for the repair, how deep it goes, and how it affects the structural integrity and value of the car.
Look at the car from multiple angles in daylight.
Look for:
A color difference may indicate a respray, but on its own it doesn't tell you why the car was painted or how good the repair is. It must be linked with an inspection of the body, the panel gaps and the bolts.
Classification: Negotiable or a warning sign
Decision: Ask for a paint thickness measurement and a professional inspection.
Compare the gaps around:
The gaps should be similar on both sides. Uneven gaps may result from a part being removed, an accident repair, or improper fitting.
Classification: Warning sign
Decision: Inspect the mounting points and the inner structure.
Look at the bolt heads for:
A removed fender or hood doesn't always mean a serious accident; it may have been taken off to replace a part or carry out a repair. But it is a question the seller should answer and the inspection should explain.
Classification: Warning sign
Decision: Link the result with an inspection of the inner structure and chassis.
This is the most important technical point regarding the body.
A professional inspection should cover:
Look for non-factory welds, bends, pulling, sections that were cut and replaced, or fresh sealant hiding a repair.
Inspecting the chassis from underneath usually requires a lift and a body expert. A structural repair can affect the car's safety, its stability, its value and its resale.
Classification: Critical
Decision if there is unexplained structural damage: Walk away or ask for a specialized engineering assessment before any negotiation.
Lift the trunk floor cover and inspect:
The trunk floor can reveal repairs that aren't visible from the outside, especially after rear-end collisions.
Classification: Warning sign or critical, depending on the damage
Decision: Link the result with the alignment of the trunk, the fenders and the rear chassis.
Look for rust:
Distinguish between treatable surface rust and structural rust that is flaking or has spread into the metal. A damp or musty smell, or pooled water, may also indicate a leak or previous flooding.
Classification: Critical if structural or caused by flooding
Decision: A professional inspection before going any further.
Check:
A tire may look fine based on its tread yet be old or cracked. A sidewall bulge or damage to the tire body is a safety problem, not just a negotiating point.
Classification: Safety
Decision: Don't rely on the car until the damaged tire is replaced.
Uneven wear may indicate:
Tire wear alone doesn't diagnose the cause. Ask for the suspension and alignment to be checked instead of simply adding the cost of new tires.
Classification: Warning sign
Decision: Check the alignment, suspension and chassis.
During the inspection and test drive, watch for:
A grinding sound, weak brakes, the car pulling to one side, or a warning light coming on needs repair and inspection, and shouldn't be ignored in exchange for a small discount.
Classification: Critical safety item
Decision: Don't complete the purchase until the cause is diagnosed.
Look for:
Suspension parts should be inspected on a lift, because a test drive alone may not reveal every worn part.
Classification: Warning sign or safety-related
Decision: Get a list of parts and the repair cost before negotiating.
Watch for:
A cold engine can reveal problems that don't show up once it has warmed up. Ask for the car to be started in front of you, and keep your hands away from the belts, fans and hot parts.
Classification: Essential
Decision: Any noise or vibration needs a diagnosis, not a guess.
Check:
The appearance of the oil alone doesn't determine the engine's age or condition; the oil may have been changed right before the viewing. However, a milky substance or visible contamination calls for an inspection of the cooling system and the engine.
Classification: Warning sign or critical
Decision: Specialist analysis and diagnosis if there is contamination.
With the engine cold, check:
Never open the cooling system cap while the engine is hot. Overheating, low coolant, coolant mixed with oil, or abnormal pressure needs to be diagnosed before buying.
Classification: Critical
Decision: Don't buy before the cooling system is tested and the cause of the problem identified.
Look for:
Distinguish between an old, dry trace and an active leak, but don't assume that a freshly cleaned engine means there are no leaks. Inspecting from underneath on a lift is more accurate.
Classification: Depends on the type of fluid and its source
Decision: Ask for a diagnosis and a written repair estimate.
Watch the color of the smoke right after starting and again once the engine reaches operating temperature.
Persistent smoke patterns may point to problems with:
But smoke color alone isn't enough to diagnose a fault. You also need to distinguish between temporary steam in cold weather and thick, persistent smoke.
Classification: Warning sign or critical
Decision: A compression or leak-down test and an electronic diagnosis when needed.
While stationary and while driving, watch for:
The transmission should be tested both cold and after the car reaches operating temperature, because some problems only appear in one of those states.
Classification: Financially critical
Decision: A specialist transmission inspection before you agree on anything.
Check:
The fault may lie in the clutch kit, the engine mounts, or parts inside the gearbox, so don't rely on a description like "light clutch" without an inspection.
Classification: Negotiable or costly
Decision: Estimate the repair cost before settling on a price.
Listen for:
In four-wheel drive cars, you should also make sure the drive systems work and that there is no inappropriate mismatch between the tires.
Classification: Warning sign
Decision: An inspection on a lift and a test drive.
Inspect:
Heavy wear combined with low mileage doesn't prove tampering on its own, but it does call for a review of the maintenance history and previous odometer readings. Inspection checklists recommend comparing the condition of the seat, pedals and steering wheel with the mileage story being presented.
Classification: Warning sign
Decision: Ask for documents that support the odometer reading.
When you turn the ignition on, the self-test lights should come on and then go off according to the car's system.
Pay attention to:
A light that doesn't come on at all can be just as much of a problem as a light that stays on. You should also check the seat belts and look for signs that the dashboard or the airbag cover has been removed.
Classification: Critical safety item
Decision: A computer diagnostic scan and a physical inspection of the safety system.
Test:
Repeat the test more than once, because some AC or window faults only appear after running for a while.
Classification: Negotiable, unless it relates to safety or visibility
Decision: Calculate the repair cost and don't rely on a verbal promise.
Pay attention to:
Taken together, these signs may point to a water leak or previous flooding, which can affect the wiring and electronic modules in the long run.
Classification: Critical if flooding is confirmed
Decision: A full electrical and structural inspection, or walk away.
Don't test drive a car on the road without making sure the test is legal and safe, that there is a valid license, and that you have a clear agreement with the owner. If there is a visible brake, tire or safety warning problem, don't take the car on the road.
During a safe test drive, watch for:
Try different engine speed ranges without driving recklessly or exceeding the speed limit.
Classification: Essential
Decision: Any unexplained weakness needs a diagnosis.
On a safe road and at a suitable speed, note:
Pulling, grinding or vibration while braking are signs that call for an inspection before buying.
Classification: Critical safety item
Decision: Stop the test drive if the brakes aren't safe.
Note:
Pulling may be caused by tire pressure, wheel alignment, the suspension or a body repair, so the cause should be diagnosed rather than assuming it is just a matter of alignment.
Classification: Warning sign or critical
Decision: Check the alignment, suspension and chassis.
After the test drive, leave the engine running for a few minutes and then check:
Some problems only appear after the car has been under load and its systems have reached operating temperature.
Classification: Final
Decision: If a new problem appears, don't treat it as a coincidence, and don't pay until it has been diagnosed.
Don't lump your notes into a general verdict like "the car is 80%." Classify each finding according to its impact.
| Result | Examples | Decision |
|---|---|---|
| Pass | Documented maintenance, normal operation, matching papers | Move on to the professional inspection and negotiation |
| Upcoming expense | Tires, battery, brake pads, scheduled service | Calculate the cost and adjust the price |
| Needs diagnosis | A leak, suspension noise, transmission jerk, warning light | Don't pay before a specialist report |
| Red flag | Mismatched numbers, chassis tampering, flooding, unclear structural repair | Stop the deal or walk away |
| Missing information | Maintenance history unavailable, unknown reason for repainting | Ask for proof and don't assume the best |
A price discount may not be enough in the following cases:
Spotting one of these signs doesn't mean you have to make a final diagnosis yourself. It means the risk has become too great to be settled by a superficial viewing.
An OBD-II reader doesn't prove that a car is sound. The absence of a visible code may mean there is no recorded fault, or that the codes were recently cleared, or that the problem isn't monitored in the way the user expects. That's why the current and pending codes and the status of the readiness tests should be reviewed, alongside an actual mechanical inspection.
After your own initial inspection, the Biddex professional inspection comes in as the second stage, and it goes through the following steps:
Instead of "good" or "acceptable," the report should classify each item into one of the following categories:
It should then present:
Checked the car yourself? Make the next step a professional inspection
Book a car inspection through Biddex to get a report on the body, the mechanics and the electronic diagnostics before paying a deposit or completing the purchase.
Remember that an inspection report describes the car's condition at a specific point in time and is not a guarantee. So make sure you understand the scope of the inspection, the parts that were not inspected, how long the report remains valid, and that the car's condition may change after the inspection date.
Don't automatically deduct the cost of every item from the car's price. Classify the findings:
Such as:
These costs can be factored into the negotiation.
Such as:
The car's price should be reassessed based on the market and the extent of the defect.
Such as:
This is not just a list of discounts. The right decision may be not to buy at all.
Suggested offer price =
The market value of a comparable car in good condition
- The cost of confirmed repairs
- The impact of defects on value and resale
- A margin of uncertainty for problems that need diagnosis
Before paying any serious amount:
Don't pay a deposit based on photos alone, and never send a verification code or bank details to someone claiming to reserve the car or arrange its shipping.
It reveals the car's condition at the time of the viewing, such as:
It shows what has been recorded in terms of:
It verifies:
None of these replaces the others. A car may be mechanically sound but have complicated paperwork, or have clean papers while hiding a structural repair.
You can carry out an initial inspection that helps you rule out unsuitable cars. But don't rely on it alone to complete the purchase, because some problems require a lift, a diagnostic device and expertise in the body, engine and transmission.
It's preferable, because it can reveal slow starting, smoke, or noises and vibrations that disappear once the engine warms up.
No. The respray may be cosmetic, due to a scratch. What matters is the reason for the respray, the extent of the repair, and the condition of the pillars, chassis and welding points.
Market terms are used inconsistently, so don't rely on a phrase like "original inner structure" alone. Ask for a specific inspection of the pillars, the engine bay, the chassis rails, the car's floor and the trunk.
No. It helps identify differences in paint thickness or the likely presence of body filler, but on its own it doesn't assess whether the body is straight, the quality of the welding, or the integrity of the chassis.
No. It reveals faults recorded in the modules it can connect to, but it doesn't uncover every mechanical or structural defect, and the codes may have been cleared before the inspection.
It may mean the battery was disconnected, the codes were cleared, or the car hasn't yet completed the required drive cycle. This doesn't prove fraud on its own, but it calls for an explanation and a re-inspection.
Not always. The odometer should be compared with the cabin's condition, the maintenance history, the car's age and its usage patterns. A lightly used car may still need fluids, tires and age-affected parts serviced.
This is up to the agreement between the two parties. Usually the buyer requests the inspection and pays for it, but the parties can agree to deduct it from the price or split it depending on the report's findings.
You can buy a car with repainted parts if the repair is clear and non-structural, the price reflects its condition, and it passes inspection. The decision shouldn't be based on the number of repainted parts alone.
Walk away or put the deal on hold if the numbers don't match, ownership is unclear, the inspection is refused, or there is major undisclosed structural damage, flooding, or a costly and unexplained safety problem.
After completing all thirty points, don't just ask, "How many items passed?" Ask:
If the car passes the initial inspection, move on to a professional Biddex inspection before paying a deposit or the full amount. If the inspection uncovers a problem with a known, safe fix, use it in your negotiation. But if the problem concerns the car's identity, chassis or safety and its impact can't be determined with confidence, walking away may be better than buying a cheap car that later becomes expensive or hard to sell.