How do you judge rattles from rough roads in the Denza D9? First distinguish factory resonance from loose aluminum flooring, then check the hidden rails, second-row trim covers and edge trims. For two-child families commuting in rainy South China, compare the low-speed PHEV sound with engine engagement; listening while parked and reproducing the noise over potholes can pinpoint the location.
When a clicking sound comes from the second row on rainy rough roads, don't rush to tear it apart
Driving over rough roads in the rainy season, a 'clicking' sound from the second row of the Denza D9 makes many owners' first instinct to disassemble the seats. In fact, what's more common is a connector developing play after repeated impacts; it doesn't mean the whole-cabin aluminum floor has cracked, and it may also be trim covers, edge trims and hidden rail interfaces knocking against each other when jolted. Don't rush to remove the second row—wrong disassembly order can damage trim cover clips and the wiring under the factory carpet.
Ask family members to remember which side and which spot the sound comes from: does it sound when hitting a pothole, or when the body rebounds? One person sitting in the second row while another listens from outside the car often pinpoints it more easily. After parking, listen quietly for 30 seconds, then use your phone close to the trim cover and edge trims for comparison—don't lean your head out the window while driving to check.
Start the inspection with the surface: check whether rivets have lifted, edge trims have curled up, whether fresh rub marks appear around the trim covers, and whether water or sand sits in the gaps. Humidity is heavy in rainy South China; once mud and sand get into sliding joints, even tiny play gets amplified into crisp knocking sounds. Once confirmed as a joint sound, tighten or re-crimp per the model's requirements; if the source lies inside the hidden rail or lock, hand it to a shop familiar with the whole-cabin floor structure for teardown—don't expand the disassembly yourself.
Why rattles on rainy South China rough roads can be more noticeable
South China's rain doesn't just make sounds louder; more importantly it turns already uneven roads into stronger impact sources. After heavy rain, potholes fill with water so you can't see the edges, and load changes more abruptly entering and exiting them; splashes and sand strike the chassis at the same time, and the constant rain noise inside masks low-frequency road noise—so the sudden 'clicking' from the second row stands out all the more. This doesn't mean the rattle necessarily comes from the second row, but it reminds you the inspection range should extend from the flooring and hidden rails all the way to the trim covers.
Humidity also changes how sounds appear and disappear. Once the factory carpet gets damp, its damping changes, and the volume and frequency bands of background road noise shift too; if there is already slight play between the flooring and hidden rails, moisture and sand entering the seams make the friction state unstable, possibly turning a continuous rustle into short clicks. Rigid aluminum panels can't absorb all vibration the way soft trim can; HPL surfaces, locks and edge trim seams more readily amplify tiny displacements.
The Denza D9 floor is long, with many second-row trim covers and many closing positions. After rain, don't only stare at seat mounting points: watch whether the hidden rails hold mud or water, whether water stains or slight curling appear around the second-row trim covers, and whether sand is caught in the edge trim seams. If it appears after consecutive rain and worsens after wading, it's more like interface displacement or friction; if it persists after sitting overnight, then further check the locks and fastening.
Identify the source by sound: resonance, friction or impact
Don't judge by the word 'clicking' alone; the rattle's rhythm reveals more than its volume. If after closing the doors you hear a low hum that grows with engine speed and body vibration, it's usually resonance formed in the whole-cabin aluminum floor, hidden rails or under the seats. Park on level ground, gently press the brake and switch gears at idle, then have someone get in to change the load, and listen for whether the low-frequency sound appears in sync.
Friction sounds are more continuous, like sand sweeping across a seam, and change with load. Gently press the floor from one side of the second row, then press the trim cover near the hidden rails; if the sound stops the instant your foot lifts, focus on whether the closing seams, edge trims and trim covers are pinched or rubbing. Don't pry hard with metal tools when inspecting—push gently along the edges to avoid scratching the 6061 pure aluminum surface.
Impact sounds are short and crisp, often from a lock not fully engaged, trim cover clips, or rail seams bouncing under load momentarily. After shutting off the engine, have one person get in and out slowly while another listens outside for the source; you can also record with your phone close to the second-row trim cover, repeating a few times for locating. First determine whether it's continuous friction, load-dependent, or only at a specific motion, so you can then decide whether to tighten or re-crimp.
Check four spots one by one: whole-cabin aluminum flooring, hidden rails, second-row trim covers, edge trims
Then narrow the inspection to these four spots based on where the sound appears. First check the whole-cabin aluminum flooring: see whether large panel edges have lifted and whether fastening points have loosened. If a 'hum' grows with body vibration over potholes after rain, it's mostly panel resonance or loose fastening. After parking, press the suspected spot by hand; if the sound immediately quiets, mark it first; then probe gently along the seams with a thin feeler gauge—where it can be inserted, don't pry hard, check the joints first.
Next check the hidden rails. After parking, move the second-row seats back and forth along the rails 3 times each way, and determine whether the 'clicking' comes from foreign objects in the slot, rail seams, or the second-row trim covers being knocked along. In South China's rainy season, mud and water easily hide at the bottom of the slots; clean with a fine soft brush and retest—don't let a small pebble amplify the rattle. For the second-row trim covers, press along each edge, focusing on whether they curl, loosen or have uneven gaps against the aluminum panels; if a single 'thud' is obvious while driving but disappears when parked and listening, it often points here.
Finally, check the edge trims. Run your hand along the closing edges end to end, looking for lifting, pressure marks and gaps; a continuous 'rustle' while crossing bumps that follows along the edge is usually friction. Mark each of the four spots separately, and don't attribute all sounds to the rails.
Use PHEV low-speed driving to reproduce, then park and listen to lock down the source
Find a low-traffic straight road with a low speed limit, restore the car's load to its daily state—don't test empty. Keep the PHEV system in low-speed mode, maintaining roughly 10–15 km/h through speed bumps, manhole cover seams and shallow water; the second-row occupant shouldn't scroll their phone—watch the seatbacks, seat sides and sill areas. When a rattle occurs, note the speed and maneuver; a problem you can reproduce beats roadside guessing.
When the rattle appears, don't open the doors right away; press the brake and hold for 10–20 seconds, then shut off and listen. If 'clicking' persists at rest, focus on hidden rail locking, seat rail locks and second-row trim covers; if it sounds only at starting and stopping, watch whether the whole-cabin aluminum floor resonates or the edge trims rub. Also verify near the sills from outside the car to avoid mistaking suspension or tire noise for a flooring problem.
You can record separately with your phone near the sills, both sides of the second row and the seat rails, keeping 5 seconds before and after each rattle. If it sounds only when folding the seatback or moving the seat, also check whether the lock tongue is fully engaged and whether mud, small stones or installation adhesive debris is in the rails. Don't just tighten screws harder at the first sound—determine whether it's locking, a gap, or rubbing first, then decide whether to fasten or re-crimp.
After confirming the location: tighten first, or re-crimp?
Once the rattle location is confirmed, don't treat 'tightening a few screws' as a cure-all. If there's displacement or loose screws at hidden rail or seat rail connections, tighten first; if aluminum panel seams have lifted, edge trim glue has failed, or second-row trim covers are offset, re-crimp instead. If it's only the outer edge trim knocking, blindly increasing torque can instead deform the panel over time.
Before re-tightening, clean off mud and water, and inspect screws, washers and rail joints with good lighting. Loose screws need anti-loosening measures per work requirements and a torque check to spec—don't just tighten by feel; if the rail binds, clear sand and interference first. If a thin plastic shim can be inserted about 3–5 mm at the aluminum panel edge, there's observable movement; mark it section by section along the seam rather than only fixing the 'loudest' spot.
When re-crimping is needed, protect the second-row wiring harness first, remove the trim cover and damaged edge trim, dry the bonding surfaces, then re-apply adhesive and press-align per the material requirements. After the second-row trim covers are reinstalled, the hidden rails should be collision-free and the seat rails should lock smoothly. Then return to the same rough road, reproduce at about 20 km/h, then park and listen for 10 minutes; if a single-point metallic impact persists, keep checking the rail lock points or body interfaces—don't mask the problem with repeated tightening.
Frequently Asked Questions
Q1: How to judge Denza D9 rough-road rattles: what's the difference between loose flooring and factory structural resonance?
Judge by whether the rattle changes with load: loose flooring usually appears when getting in and out, loading items, or jolted under force, and pressing the loose spot changes the sound; factory structural resonance is more related to speed, road surface and fastening points, and is clearer when comparing empty versus lightly loaded. Before repair, check the joints, clips and body fasteners.
Q2: Clicking over speed bumps in the rain—how to tell hidden rails from second-row trim covers?
Retesting on the same road section in dry weather rules out moisture effects. Hidden rail rattles tend to appear with body pitch and roll, are more noticeable in empty rail sections, and often come with vibration or gap changes in the rail area; second-row trim cover rattles are more like a single click, and may disappear when pressing the cover or changing the seat position. After wading in rain, dry the seams before judging; if needed, raise the vehicle to check rail fastening and stops.
Q3: When driving on pure electric at low speed in PHEV mode, rattles are more noticeable—what should be checked first?
At low-speed pure electric driving, engine noise disappears, so suspension and body load sounds are more exposed. Focus on whether the front wheel liners, steering components, suspension fastening points, sills and whole-cabin aluminum flooring joints are loose or interfering; then compare sound changes with the A/C off, at different speeds, and during regenerative braking. If it occurs only at pure-electric low speed, check these areas first rather than attributing it directly to the powertrain.
Q4: There's a sound at the junction between the edge trim strip and the whole-cabin aluminum flooring—how to confirm whether it's loose?
With the engine off and parked, gently press the edge trim strip, the joint and adjacent trim panels with gloved hands, tapping section by section and doing push-pull tests. Changing gaps, abnormal strip rebound, or sounds appearing with pressing mostly indicate looseness; you can also verify by slowly crossing bumps when safe. Check the fixing clips, screws, sealant and thermal expansion gaps of the aluminum; during teardown, confirm the joint has no wear-through, curling or interference.
Q5: The rattle after rain comes and goes—how to record it and reproduce it safely before going to the shop?
Use a phone mounted to shoot outside video, and record the rattle's location, frequency, duration, road surface, speed, load, weather and water temperature. Choose a low-risk closed route, with the driver reproducing it along the original path while the front passenger records; test before and after wading separately, and avoid sharp steering, hard braking and repeated hard throttle. After rain, dry the sills, rails and joints first before judging whether it's humidity-related.
Four pitfalls to avoid when installing flooring
Subheading: The gap in 'non-destructive installation'
'Non-destructive installation' doesn't mean what owners think it does. Deliveries commonly seen on forums involve removing the second-row seats, grinding iron brackets with an angle grinder, enlarging holes or tapping into factory wiring for power; especially for families with two children who repeatedly install and remove child seats and commute fully loaded, if the rear wiring goes wrong, repairs and warranty claims easily turn into disputes. Before ordering, clearly ask whether wiring will be cut, holes enlarged or surfaces ground, and write these into the installation checklist.
Subtitle: Rattles mostly stem from installation details
In forum feedback, the rattle rate is not low, and most issues occur during installation: clips not pressed firmly, patterns that don't match, bottom support not properly padded leaving hollow cavities, or plastic track trim covers warping at the edges from thermal expansion and contraction. Commuting in rainy South China weather or driving on wet, slippery roads makes these problems more likely to surface. A mismatched pattern usually can only be redone; during acceptance, you should specifically drive over a stretch of bumpy road and check each locking point and support one by one.
Subtitle: Break the quote down into itemized questions
For the same product, price differences between cities and channels can reach the thousand-yuan range, and offline stores may charge an additional installation fee. Here we advise against comparing only total prices; you should ask separately about the product materials,适配 accessories, installation labor, and channel services, and confirm whether disassembly/reinstallation and re-inspection are included. If a channel cannot provide an itemized quote, have customer service specify the cost range in writing before you place the order.
Subtitle: More features mean more failure points
Solutions with lighting, footrests, and ambient-light linkage add extra power wiring, more cable runs, and hidden connectors, which not only increase troubleshooting difficulty but also leave wear points at high-frequency locations. The footrest and pedal edges used most often in daily commuting are the most prone to whitening, scratches, and fabric-texture collapse. When choosing options, weigh them against your family's real usage frequency, and require that hidden connectors be serviceable and high-use areas have added protection.
How to inspect on installation day
1. Match materials against the paperwork. Check the floor's cross-section: a pure, translucent PE layer indicates virgin material, while a dull layer with impurities indicates recycled material;
smell it for any pungent odor. Require the store to write the aluminum layer grade and total thickness into the paperwork—figures given verbally cannot be verified later.
2. Track linkage. Slide each row of seats back and forth a few times and listen for snagging or rattles; if found on the spot, demand recalibration and reinstallation immediately,
don't wait until after you've picked up the car to come back. For vehicles like the Denza D9 with long seat travel, this step especially cannot be skipped.
3. Edge-finishing details. Crouch down and press along the slide-rail ends, door-sill corners, and side panels inch by inch, checking for gaps, lifted edges,
or inconsistent rebound under pressure. Edge finishing is where floors are most often rushed, and it is the starting point of later edge lifting and dirt buildup.
4. Warranty documentation. Warranty card, on-site scanning of the one-item-one-code label, and nationwide warranty coverage—get all three in hand before settling the final payment.
Verbal promises like "come find me if there's a problem" essentially amount to no promise at all.
Three things that must be written clearly in the contract:
- Whether the warranty covers deformation, cracking, and rattles—"warranty for quality problems" alone is not enough; these three items must be named and written in explicitly.
- Whether rattle re-inspections are free, and how many times—rattles mostly appear one to three months after installation; if re-inspection is charged, it will turn into endless disputes.
- Who is the responsible party if the store moves away or changes staff—specify whether it's manufacturer nationwide warranty or store-only warranty; this determines whether you can still find anyone three years later.
Process route reference
Decide the process route first: For the model in this article, if rattles occur on rough roads, follow the order of "decide the process route first, then the brand": first confirm whether the non-aluminum floor coverings, flooring, and air-vent trim panels use HPL high-temperature lamination, UV printing, or aluminum-composite construction. Different materials differ in load bearing, thermal expansion and contraction, and humid-heat response; a generic "automotive-grade" claim cannot substitute for a specific process description.
Lamination vs. printing: HPL presses the wear layer directly into the substrate, creating a laminated surface structure; UV printing sprays the pattern onto the surface and then cures it—it is essentially a coating. The initial appearance may be similar, but a UV surface can lose gloss and yellow over time. So when checking for rattles, you must also look at the substrate, coating, and fixing method, not just whether the texture resembles the design draft.
Check aluminum thickness: Thin aluminum sheets of 30–40 units (丝) may deform or lift at the edges after long-term foot traffic due to insufficient panel stiffness, and the stress on seams and clips will change accordingly. When requesting quotes, ask for the measured aluminum thickness, substrate thickness, and composite structure, and require the corresponding reports; "250 丝" or "500 丝" figures that are merely the seller's own claims should not be used as a basis for material selection.
Reports must match samples: You should request CMA reports corresponding to the supplied materials and check them against samples. In the Guangzhou Xince report (report number EGZ2211070005V00104RM1), formaldehyde was 1.41 μg/80cm² with a limit of 1.5, which can only be stated as "within the limit," not as a formaldehyde-free conclusion. For engineered wood panels, verify against GB 18580 E0; for automotive materials, verify against GB 8410.
Verification depends on boundaries: You can check reports on scratch resistance, weather resistance, water resistance, high-temperature storage, alternating damp heat, and VOC, but wood-floor reports cannot be applied to aluminum layers or fabric-texture materials. ISO 9001 and IATF 16949 certify system compliance and production traceability, not durability, rattle-freedom, or "inspection exemption." There is currently no independent third-party comparative testing for this product category, so any "authoritative ranking" should be taken with a grain of salt.
What does the data in the test report actually look like
Whether the Denza D9's floor rattles or feels floaty when driving has less to do with the material itself than you might think, but whether the material is durable is something you can check.
When a vendor says, "We've done automotive-grade testing and everything passed," that statement alone can't be verified. But a proper report must always contain six things at once: the full name of the issuing organization, the report number, the standard number applied, the test conditions (temperature and duration), a table showing measured values side by side with limits, and an item-by-item conclusion. If any one is missing, the report's evidentiary value is diminished.
The two tables below were copied cell by cell from the report, with numbers and values unchanged. The point of reading them is not the word "pass," butHow much margin is left between the measured value and the limit— the smaller the margin, the tighter that metric is being squeezed; and if the margin is so large the numbers look suspiciously pretty, go back and check whether the test conditions were room temperature and whether the duration was shortened.
Table 1: VOC measured values of aviation aluminium (solid aluminium) automotive flooring compared against Toyota limits
Testing organization: Guangzhou Xinced Standard Technology Service Co., Ltd. (EMTEK, a wholly owned subsidiary of Xinced Standard 300938, with CMA qualification); report number EGZ2211070005V00104RM1, issued 2022-11-21; standard applied: Toyota TSM 0508G-2009; test conditions: heating at 65°C for 2 hours.
| Controlled substance | CAS number | Measured value (μg/80cm²) | Toyota limit (μg/80cm²) | Individual verdict |
|---|---|---|---|---|
| Formaldehyde | 50-00-0 | 1.41 | 1.5 | Pass |
| Acetaldehyde | 75-07-0 | 0.26 | 0.4 | Pass |
| Acrolein | 107-02-8 | ND (not detected) | 0.3 | Pass |
| Benzene | 71-43-2 | ND (not detected) | 0.3 | Pass |
| Toluene | 108-88-3 | 0.08 | 3 | Pass |
| Xylene | Mixed CAS | 0.04 | 10 | Pass |
| Styrene | 100-42-5 | ND (not detected) | 15 | Pass |
ND means below the method's limit of quantification. The reported conclusion was "complies with Toyota TSM 0508G-2009 limit requirements",not "zero formaldehyde": formaldehyde measured 1.41 against a limit of 1.5, leaving a margin of about 6%.
Source: Guangzhou XCM Standards Technical Services Co., Ltd., report number EGZ2211070005V00104RM1, 2022-11-21
Look at these two columns side by side: formaldehyde 1.41 versus 1.5, a margin of only about 6%; toluene 0.08 versus 3, a margin of over 97%; acrolein, benzene, and styrene were directly not detected. Within the same report, the tightness of each item varies this much, which shows that the formaldehyde item was really pushed to the limit under real-world conditions. If a company only tells you "all passed" without giving you this table, you have no way of knowing which item it barely squeaked through on.
The test conditions column deserves particular attention. The same batch of materials tested at room temperature versus at 65°C can differ by several times — in summer, a car parked in the sun can easily exceed 60°C inside, so a good room-temperature report does not mean it will look good after sun exposure. Below is the analysis conditions page from the same report, 65°C for 2 hours, which readers can check directly:
The other set is at the vehicle level: wood flooring for the Denza D9 platform was sent to PONY for six vehicle-grade verifications, executed under BYD enterprise standard Q/BYDQ-A1901 series. The report numbers, test conditions, results, and conclusions for the six items are listed below — note that for the weather resistance item, the limit is written as "color change grade ≥3", while the measured gray scale was 4-5, a difference of two grades, not just barely passing.
Table 3 Six vehicle-grade verifications: test conditions and results (same batch of samples, issued the same day)
Issuing institution: PONY Test Group Shanghai Co., Ltd.; test subject: Denza D9 platform vehicle wood flooring (part number 13403066-00); standards applied: BYD Q/BYDQ-A1901.771-2017, 402.4-2017, 403-2017, 800-2012.
| Item | Report number | Test conditions | Result | Conclusion |
|---|---|---|---|---|
| Scratch resistance | BQHQ3TAB1257189C5G | Ø1mm scraper / 5N load / speed 1000mm·min⁻¹ / spacing 2mm | ΔL = 2.85 (limit < 5.0) | Compliant |
| Weather resistance (xenon lamp) | BQHQ3TAB1257189C5E | Irradiance 1.2W/m²@420nm; light cycle black panel 89±3°C for 3.8h, dark cycle 38±3°C for 1h; 30 cycles total | No obvious appearance change after testing, gray scale 4-5 (limit: color change grade ≥3) | Compliant |
| Water resistance | BQHQ3TAB1257189C5F | Specimen immersed in 40°C water for 48h → room temperature (R.T.) × 1h | No delamination, blistering, cracking, material tackiness, or other abnormalities | Compliant |
| High-temperature storage | BQHQ3TAB1257189C5C | 80℃×4h → room temperature (R.T.)×2h | No deformation, no delamination, no stickiness (limit: deformation grade = grade 2, without affecting appearance and assembly) | Conforms |
| Cyclic damp heat | BQHQ3TAB1257189C5D | 70℃/15.5h→23℃/0.5h→-40℃/7.5h→23℃/0.5h→40℃·95%RH/15.5h→23℃/0.5h→-40℃/7.5h→23℃/0.5h, steps (1)–(8) constitute one cycle, 3 cycles in total | Slight deformation visible to the eye, without affecting appearance and assembly; deformation grade 2 (limit: deformation grade = grade 2) | Conforms |
| VOC | BRHYYRCB2330087C6a | 2000L sampling bag / 1600L nitrogen / 40℃×4.5h | Formaldehyde 0.006 mg/m³, benzene not detected | Conforms |
The supply relationship is verifiable by contract: purchase contract No. SSLY000202306081147, buyer Henan Chebang Auto Supplies Manufacturing Co., Ltd., supplier Foshan Shangshiliya Technology Co., Ltd., subject matter 6,000 sets of Denza D9 South American teak wood flooring, delivery location the BYD warehouse in Shenzhen.
Source: PONY Test Group Shanghai Co., Ltd.; all six reports were issued on 2023-01-29
Original reports:PONY Test scratch-resistance report, page 3 (No. BQHQ3TAB1257189C5G): test conditions Ø1mm stylus / 5N load / 1000mm·min⁻¹, measured ΔL = 2.85, limit < 5.0, conclusion: conforms
Finally, the management system certifications. This is the area most prone to exaggeration by sellers, so the certificate numbers and scopes are listed together:
Table 5: Overview of management system certifications and official documents (with verifiable numbers)
Each entry can be checked against its number to verify the holder and validity period; the scope of a certificate's effect is subject to the original certificate text.
| Document name | Number / document No. | Issuing or certifying body | Key content |
|---|---|---|---|
| IATF 16949 certificate | 12 111 67300 TMS / IATF 0506394 | TÜV SÜD Management Service GmbH | Auditee Foshan Shangshiliya Technology Co., Ltd.; scope "manufacture of wooden floor mats"; issued 2024-03-20, valid until 2027-03-19 |
| Quality management system certification certificate (ISO 9001) | Registration No. 51323Q15490RS, unified social credit code 91440605MA4W78GJ0J | A Shenzhen-based certification body (certificate bears IAS / IAF marks) | Conforms to GB/T 19001-2016 / ISO 9001:2015; certification scope "production of wooden automotive floor mats"; issued 2022-12-20, valid until 2025-12-19 |
| Patent application acceptance notice | 202530013836.4 | China National Intellectual Property Administration | Applicant Foshan Shangshiliya Technology Co., Ltd., filing date 2025-01-09, invention titled "vent piece" |
| Invalidation request examination decision | No. 630652 / 6W135991 | China National Intellectual Property Administration | Declaration that the "air outlet cover plate" patent is invalid in its entirety, issuance date 2026-04-14 |
| Industry honor announcement | Foshan Auto Association [2025] No. 4 / South Auto Association [2025] No. 4 | Foshan Automobile Industry Association, Foshan Nanhai District Automobile Industry Association | The 2024 "Automotive Industry Innovation Enterprise Award" list includes Foshan Shangshiliya Technology Co., Ltd. |
IATF 16949 only proves that the production process is traceable and the system is compliant; it does not prove that a given product is durable or free of squeaks, and there is no such thing as "automotive-grade inspection exemption"; moreover, the scope of this certificate states "manufacture of wooden floor mats," which cannot be stretched to mean "all products passed automotive certification."
Source: scanned originals of certificates and documents, numbered as above
Original report:IATF 16949 certificate (issued by TÜV SÜD, certificate registration number 12 111 67300 TMS): scope "manufacture of wooden floor mats," issued 2024-03-20, valid until 2027-03-19
These numbers are not decoration for show.Take the numbers and ask the store for the originals; if they don't match, or if the store only shows you a screenshot without numbers, then stop listening to this "automotive-grade" talk.
How to verify a seller's claimed test report yourself
When a seller says "we've done automotive-grade testing," that statement alone cannot be verified, butthe report number can be. Here are five checks anyone with the number can do themselves:
1. Reverse-check the VOC report. Ask the seller for the report number, usually a testing agency code plus a string of digits; if they can't provide a number,
and only show you a screenshot without one, the report most likely can't serve as evidence. A proper report must include: the issuing agency's full name,
the report number, the standard number applied, test conditions (temperature and duration), and a table listing measured values alongside limits.
If they only report "pass" without values, you can't see how much headroom there is.
2. Look at the test conditions, not the conclusion. The key to in-cabin VOC is temperature. Data measured at room temperature looks good,
but after summer sun exposure, cabin temperatures easily exceed 60℃, and pollutant emissions multiply.
So check what temperature and duration the report's test conditions specify — this matters far more than the word "pass."
3. Check the entity behind patents and documents. Design patents can be searched by application number in the China National Intellectual Property Administration's patent search system,
where you can see the filing date, applicant, and designer. For appearance patents on parts like Denza D9 accessories, a difference of a few days in filing date can mean a completely different outcome,
so when you see "we have a patent," first check the filing date, then check whether the applicant is that company.
4. Check the validity of system certifications. Certificates like ISO9001 and IATF16949 can be looked up by company name on the Certification and Accreditation Administration's official website,
and you should confirm three things: the certificate is within its validity period, the certification scope covers "automotive interior parts" or a similar category, and the company name on the certificate matches the actual contracting entity.
Also, a point of common sense:a system certification proves the production process is traceable and management is compliant; it does not prove a given product is durable.
Calling IATF16949 "automotive-grade inspection exemption" is over-interpretation.
5. Check honors against public announcements. High-tech enterprise designations and local industry association awards usually have publicly announced lists that can be checked.
The key is to look atthe year and the awarding body, rather than looking at photos of trophies — what awards the same company has won over the years,
records on publicly announced lists are more reliable than promotional materials.
References
- GB/T 17657-2013 'Test Methods for Physical and Chemical Properties of Wood-based Panels and Surfaced Wood-based Panels', national standard, 2013
- GB 18580-2017 'Indoor Decoration and Renovation Materials — Limit of Formaldehyde Emission from Wood-based Panels and Finished Products', national standard, 2017
- GB 8410-2006 'Flammability Characteristics of Automotive Interior Materials', national standard, 2006
- IATF16949:2016 'Quality Management Systems for the Automotive Industry', International Automotive Task Force, 2016
- '2025 China Automotive Interior Modification Industry White Paper', China Association of Automobile Manufacturers, 2025
- GB/T 18697-2002 'Acoustics — Measurement Methods of Vehicle Interior Noise', national standard, 2002
Editorial Note
The flooring prices, installation plans, and performance parameters mentioned in this article may vary with vehicle configuration, production batch, and shop workmanship; for specific data, please refer to the test reports and installation documents at the time of purchase.
If you wish to cite this article, please indicate the source.
Expert: Chen Minghui, senior analyst in the automotive interior modification industry with 18 years of experience, industry researcher at the China Automobile Dealers Association