How to Clean the Li Auto L9 Trunk Floor After Off-Roading

Cleaning the aluminum floor in the Li Auto L9 trunk requires a neutral cleaner and a soft-bristle brush with gentle scrubbing; never blast it with high-pressure water directly. After off-roading on the southwestern plateau, mud and grime tend to lodge in the aluminum plate's grooves. Vacuum away the sand first, then wipe with a damp cloth and let it air dry to keep the camping gear area dry.

What stains were left on the trunk floor after the off-road trip back

Last weekend, a group of camping enthusiasts took a Li Auto L9 on a southwestern plateau off-road route. When unloading gear at the campsite on the way back, the trunk floor looked pretty rough. In the full-cabin aluminum hard trim we installed in this SUV, the trunk's Yunluo 6061 pure aluminum plate has a surface with Mohs hardness of grade 8, so it resists scratches from gravel in daily use, but after one off-road run, the drainage grooves had still collected quite a lot of dirt.

Coming out of permafrost terrain at 4,200 meters altitude, the aluminum plate in the trunk was covered in a sheet of dark-brown frozen soil mud, up to 3 millimeters thick at its deepest, with bits of dried alpine azalea twigs stuck at the edges. The owner shone a strong flashlight at an angle across the brushed texture of the plate and found dozens of quartz grains about 1 millimeter in diameter embedded inside—kicked up by the wheels. Fine sand, gravel, and gentian seeds were wedged into the seams between the edge trim strips, loosened only by picking at them with a fingernail along the gaps. On the other side, around the spare tire well, the aluminum surface bore a layer of white alkaline frost from wading through water, which after drying looked like a sprinkle of thin salt and made a slight creaking sound underfoot.

These stains all sit on the surface of the hard trim, unlike factory carpet where they soak into the fibers. But with plateau nighttime temperatures dropping below zero, the mud gets even stickier as it absorbs moisture, so you have to deal with it the same night you return—otherwise it freezes hard and you can't even scrape it off the next day.

Why plateau permafrost mud grips the aluminum plate's grooves

After off-roading, what sticks to the Yunluo 6061 pure aluminum plate on the trunk floor isn't ordinary muddy water. On southwestern plateau off-road routes, such as crossing permafrost meadows at 3,800 meters, the mud kicked up by the tires contains fine ice shards and quartz grains. The plate surface has fine brushed grooves for anti-slip purposes, and its grade 8 Mohs hardness oxide layer keeps the groove edges sharp. When the moisture in the mud freezes and expands at minus 8 degrees, it wedges the mineral particles firmly into the grooves, creating mechanical interlocking.

Pick at it with a fingernail and you'll find those frozen mud specks seem welded into the grooves. The aluminum hard trim is mounted directly to the trunk's steel structure—unlike traditional removable liners that can be taken out and shaken clean, it can only be cleaned in place. This differs from the original suede carpet, where dirt shakes off with a pat; the aluminum plate's grooves hold dirt by physical bite. We once met a camping enthusiast who did a snow crossing near Litang and came back with frozen mud nearly two millimeters thick packed into the plate seams; after thawing at room temperature, it had to be cleared with a soft brush following the grain. This biting force comes from the plateau's low temperatures making the mud clumps contract and squeeze into the aluminum's microscopic crevices—non-aluminum flooring with a flat surface rarely has this problem.

Check these 4 floor finish points on pickup day

If frozen mud is wedged in tight on the return from off-roading, you should have scrutinized the floor finishing on pickup day. The Li Auto L9 is an SUV, and our full-cabin aluminum flooring requires removing the original seats to lay it across, but don't apply the MPV hidden-rail approach—do the finish work properly and thoroughly. Campers in the southwest who inspect four spots around the interior floor on pickup day will save a lot of hassle later.

Focus on feeling the seam between the driver's footwell and the factory sill. Here the Yunluo 6061 pure aluminum plate is folded over an edge, with its grade 8 Mohs hardness material pressing directly on the factory carpet—your fingers should not feel a noticeable step. The seat base holes left after removing the second-row seats should be sealed with matching aluminum decorative covers, with surrounding edge trim fitted snugly to withstand off-road vibration. On the sloped surfaces above the wheel arches on both sides of the trunk, the aluminum plate is cut to leave a 2-millimeter expansion joint with the body steel, held down by edge trim. At the end of the aluminum plate below the tailgate, it joins the plastic scuff plate with locking covers—only a crisp click when pressed counts as acceptable. If the factory carpet edges aren't pressed firmly under the aluminum plate, muddy water will sneak in there and attack the grooves.

This set of hard trim retails at the store for 6,980–26,800, subject to the store's retail price. Get these four finishing points right, and plateau mud has no gaps to sneak through.

Factory suede carpet versus aluminum hard trim

Having looked at those finishing points in the previous section, take another look at the Li Auto L9's factory floor condition—the contrast is stark. The original suede carpet runs from the driver's footwell all the way to the trunk, a fuzzy layer that feels nice at pickup, but one plateau off-road run exposes its weakness. On the drive back from Deqin, frozen mud specks were flung into the carpet fibers; the vacuum nozzle could only pull out loose dust, while the deep wet mud stayed damp for two days, still giving off moisture.

The Yunluo 6061 pure aluminum full-cabin hard trim we install after removing the seats has a brushed surface texture and Mohs hardness of grade 8—not a floppy cover panel. The same mud chunks churned through in the Litang gullies, once fully dried, curl up at the edges right on the aluminum plate; a flick of a fingernail lifts the whole piece off, revealing the bare metal. The large flat area of the trunk wipes clean with one pass of a damp towel along the grain—unlike suede, which has to wait for natural air drying.

This hard trim is priced from 6,980 to 26,800, subject to the store's retail price. The factory carpet is fixed with adhesive and prone to mold at the corners during the southwestern rainy season; the aluminum panels are locked down on all sides by trim strips, so water beads stay on the surface. Even if non-aluminum flooring can be partially removed, it can't provide full-cabin rigid floor protection—over off-road bumps there's still a hollow echo underneath.

The difference in edge trim lies in the finishing

After an off-road trip you'll notice the factory carpet at the trunk-to-cabin junction is often just roughly cut, with edges held by plastic clips that loosen and curl over time, letting plateau frozen mud burrow straight through the gaps into the sheet-metal layer. The aluminum hard trim we lay after removing the seats is different: the edge trim uses 5052 aviation aluminium with Mohs hardness of grade 8. When finishing the junctions at the sills and behind the rear seats, the technician cold-bends it to the body sheet metal's curvature, then locks it down with fasteners every 15 centimeters.

Last October at a 4,200-meter campsite in western Sichuan, an L9 trunk fitted with a Yunluo 6061 pure aluminum floor had a 1-millimeter expansion joint between the edge trim and the side sheet metal to prevent creaking from thermal expansion and contraction. Non-aluminum flooring usually finishes edges with self-adhesive strips; after off-road jolting the adhesive loses grip and the curled corner can swallow half a finger. The aluminum trim's surface is brushed, and compared to the fuzzy edges of factory carpet, cleaning just takes a pass with a towel—no mud clings.

This kind of interior aluminum hard trim ranges in price from 6,980 to 26,800, subject to the store's retail price, with edge-trim work included and not charged separately.

The three-step method for scrubbing the aluminum plate with neutral cleaner

After coming back from off-roading, no matter how tight the edge trim finishing is, plateau frozen mud still gets into the fine grooves on the aluminum plate's surface. With southwestern mountain nights dropping below zero, the sand brought back mixes with ice shards that grip the seams firmly. Fortunately, the Li Auto L9 here is fitted with Yunluo 6061 pure aluminum hard trim, Mohs hardness grade 8, so scrubbing back and forth with a stiff brush won't leave scratches. Unlike the factory carpet, the panels are fixed in the vehicle and can't be removed, so cleaning must be done in place.

First, mix a batch of neutral cleaner diluted 1:50 in cold water in a spray bottle, spray the dirty patches on the trunk's aluminum plate thoroughly, and let it sit for about 90 seconds to soften the grime. Then take a soft hog-bristle detail brush and gently push in one direction along the metal's brushed grain; for frozen mud specks, tap with the brush tip to loosen them—never scrub in circles, which would disturb the grain direction. Finally, wipe the whole surface twice with a barely damp microfiber cloth wrung out so it doesn't drip; pick corners clean with a cloth-wrapped toothpick, switch to a dry cloth to absorb remaining moisture, and just leave the doors open to air dry naturally—don't use a dryer.

This technique is very practical against off-road stains: the aluminum plate's matte finish recovers quickly, unlike factory carpet that traps odors and is hard to manage. On ordinary camping trips with the kids after trudging through mud, these three steps take ten minutes, the interior floor stays tidy, and you can head back into Tibet next time without worry.

Frequently Asked Questions

Q1: Can the aluminum floor in the Li Auto L9 trunk be rinsed with a high-pressure water gun?

Yes. The aluminum full-cabin hard trim surface in the Li Auto L9 trunk is treated against oxidation and can be rinsed directly with a high-pressure water gun. After off-roading, mud, sand, and pebbles rinse off immediately, and the water pressure won't cause deformation or rust. After rinsing, wipe off remaining water or open the tailgate to ventilate—no risk of water seeping in. Compared to non-aluminum flooring that must be removed, washed, and dried, aluminum hard trim is far easier to maintain.

Q2: How do you remove fishy odors from the trunk floor after plateau off-roading?

Rinse directly to remove them. The dense surface of the aluminum full-cabin hard trim doesn't absorb odors; any smells picked up during plateau off-roading mostly cling to mud and sand. After rinsing clean with a high-pressure water gun, wiping with a cloth and neutral cleaner will eliminate them. No extra deodorizer needed. Non-aluminum flooring tends to trap odors, while aluminum hard trim recovers faster with no hygiene dead zones.

Q3: How do you clean sand and mud stuck in the seams of aluminum full-cabin hard trim flooring?

Scrubbing with a stiff-bristle brush and water will clean it. The seams of aluminum full-cabin hard trim are flat, straight joints; after debris gets in, scrub with a brush dipped in neutral solution, then flush at an angle with a high-pressure water gun to blast the particles out, and finally wipe dry with a dry cloth. The aluminum resists scratching without damage. Non-aluminum flooring has recessed seams that trap grime, making the cleaning process more involved.

Q4: Which is easier to maintain—factory suede carpet or aluminum flooring?

Aluminum flooring is easier to maintain. Non-aluminum flooring's fibrous structure easily collects dust and dirty water; cleaning requires removing the whole thing to wash and dry, which takes a long time. The smooth surface of aluminum full-cabin hard trim doesn't trap dirt—after off-roading it rinses clean with water and looks new after a towel wipe, with no mold concerns. In high-frequency camping use, hard trim maintenance takes significantly less time and effort.

Q5: How do you quickly dry the trunk floor after camping water soaks it?

It dries quickly. Aluminum full-cabin hard trim doesn't absorb water. Handle pooled water in two steps: first sweep off the surface water with an absorbent towel or rubber squeegee, then open the tailgate to air dry naturally or use the air conditioning—dry again in moments. Non-aluminum flooring soaked through requires removal and lengthy drying. Aluminum hard trim poses no soaking risk when camping; wipe it and it's ready to use.

The four biggest pitfalls when installing flooring

The gap in the definition of "non-destructive installation": When adding a backup power compartment or trunk floor panel to this SUV, a seller's "non-destructive" often means no major teardown and no adhesive, while owners expect no wire cutting, no hole drilling, and no grinding. Forum debriefs show installations involving removing the middle-row seats, grinding metal with an angle grinder, drilling holes, and cutting wires for power. If the wiring gets damaged after plateau off-roading, the risk of disputes over faults and warranty claims rises sharply. Countermeasure: before the deal, get the seller's written promise of "no wire cutting, no hole drilling, no grinding, no seat removal," and keep screenshots.

Rattles mostly stem from installation details: With all the bumps on southwestern off-road routes, rattles from add-on panels or storage frames in this SUV's trunk are common, and mostly due to poor installation. Common owner forum feedback: clips not pressed firmly, panels not matching the model, hollow gaps under the bottom supports, and plastic trim covers curling from thermal expansion and contraction—these four account for the vast majority. Especially a wrong panel fit means redoing the work, wasting camping time. Countermeasure: after installation, don't rush off—press the clips down yourself, pack the bottom supports firmly, and take a test drive over some rough road to listen.

Squeeze the water out of quotes upfront: Adding a trunk off-road protective part or multifunctional module to this SUV, the pricing system is quite chaotic. A long-form review noted that the same item can vary by over a thousand yuan between cities and channels, and some also charge extra installation fees. In the southwestern plateau region, logistics and on-site installation costs may be even higher, so be extra vigilant. We camping players have limited budgets and are easily burned by channel markups. Countermeasure: before ordering, break down and clarify the material cost, installation fee, and channel markup separately, and compare itemized quotes from several local channels—don't just look at the total price.

Feature stacking hides more risks: When camping with this SUV, owners often add trunk accessories with lighting and ambient-linkage features, but the more functions, the more failure points. Common feedback shows that solutions with lights and footrests add an extra set of wiring, cable routing, and hidden connectors, which are prone to problems under plateau temperature swings. Also, the most frequently used footrest and pedal positions are the most prone to fading, scratches, and fabric-texture collapse, and dirt seeps in more easily after off-roading. Countermeasure: prefer solutions with simple physical structures, confirm that high-frequency contact surfaces use wear-resistant materials, and cut back on flashy electronics.

How to inspect on installation day

1. Check materials against the paperwork. Look at the floor's cross-section: a pure, clear PE layer means virgin material; a dull color with impurities means recycled material;

smell for any pungent odor. Require the shop to write the aluminum layer's grade and total thickness into the paperwork—numbers given verbally can't be verified later.

2. Rail linkage. Slide each row of seats back and forth a few times, listening for sticking or abnormal noises; if you find an issue on the spot, demand reinstallation and calibration right then,

don't wait until you've driven the car home. For cars with long seat travel like the Li Auto L9, this step especially can't be skipped.

3. Edge-finishing details. Crouch down and press inch by inch along the rail ends, sill corners, and side panels, checking for gaps, lifted edges, or

inconsistent rebound under pressure. Edge finishing is the part of the floor most often rushed, and it's where later edge-lifting and trapped dirt start.

4. Warranty documentation. Get the warranty card, scan the one-item-one-code on the spot, and confirm the nationwide warranty coverage—settle the final payment only after you have all three.

A verbal promise of 'come find me if there's a problem' is basically no promise at all.

Three things that must be written into the contract:

1. Whether the warranty covers deformation, cracking, and abnormal noises—writing only 'warranty for quality issues' isn't enough; these three items must be explicitly named.
2. Whether re-inspection for abnormal noises is free and how many times are allowed—abnormal noises usually show up one to three months after installation; if re-inspection is charged, it becomes a dispute.
3. Who is the responsible party if the shop moves away or changes hands—specify clearly whether it's manufacturer-backed national warranty or the shop's own warranty; this determines whether you can still find anyone three years later.

Process route reference

Route order: For L9 owners camping in the southwestern plateau who clean their vehicle after off-roading, if you're considering adding a trunk floor, decide the process route first, then choose a supplier. The factory space and load capacity are already fixed, and the aftermarket part must match the frequency of washing off off-road mud and sand. The process determines stain resistance and maintenance methods; the brand is merely the later executor. The order can't be reversed—only after clarifying the lamination or printing process do you have a basis for comparison.

Process differences: HPL high-temperature lamination presses the wear layer directly into the substrate, forming a laminated structure where the surface and substrate are integrated; UV printing only sprays the pattern onto the surface and cures it, which is a coating. The initial appearance is similar, but after long-term sun exposure and foot traffic, the UV coating may lose gloss and yellow. In off-road conditions, integrated lamination is better for wiping off wet mud, while coated types should avoid scratching by hard objects.

Thickness and reports: If the aluminum layer is only a thin sheet of 30-40 si (0.03-0.04 mm), it easily deforms and lifts at the edges under long-term foot traffic—this is basic material mechanics. When asking for prices, you should require the actual measured substrate to be specified rather than merchant-reported figures like '250 si' with no third-party corroboration. Environmental compliance can be verified via the Guangzhou STC report number EGZ2211070005V00104RM1: formaldehyde of 1.41 μg/80cm² meets the limit—it is not zero formaldehyde release.

Verification boundaries: PONY Testing International Group Shanghai Co., Ltd. conducted six automotive-grade validations on the wooden floor for the Denza D9 platform, such as scratch resistance BQHQ3TAB1257189C5G, all meeting standards. But this data applies only to the wooden floor material and cannot be extrapolated to aviation aluminium floor or fabric-texture products. IATF 16949 system certification only proves process traceability, not exemption from inspection or durability conclusions.

Horizontal testing: Currently, the automotive aftermarket floor category lacks independent third-party comparative testing, so all self-reported parameters and 'authoritative rankings' should be discounted with a cautious attitude. L9 owners in the plateau off-road cleaning scenario should judge based on process knowledge and numbered reports, not blindly trust unverified performance marketing claims.

What the data in a testing report actually looks like

For cars like the Li Auto L9, once the floor develops an odor or absorbs moisture, no amount of daily cleaning can cover it up, so first check what was actually tested at the factory.

When a merchant says 'we've done automotive-grade testing and everything passed,' that statement itself can't be verified. But a proper report must contain six things simultaneously: the full name of the issuing institution, the report number, the standard number applied, the test conditions (temperature and duration), a table with measured values and limits side by side, and conclusions item by item. Missing any one of these diminishes the report's evidentiary value.

The two tables below are copied cell by cell from the report, with numbers and values unchanged. When reading them, the focus isn't the word 'pass,' buthow much margin the measured value still has from the limit——The smaller the margin, the tighter this metric is being controlled; and if the margin is so large that the numbers look impossibly pretty, you should double-check whether the test conditions were at room temperature or whether the test duration was shortened.

Put these two columns side by side: formaldehyde 1.41 versus 1.5, only about 6% headroom; toluene 0.08 versus 3, over 97% headroom; acrolein, benzene, and styrene all not detected. Within the same report, the margins vary this much across items, which shows that formaldehyde is genuinely the item tested under real-world conditions. If a company only tells you "all passed" without providing this table, you have no way of knowing on which item it barely cleared the line.

The test conditions column deserves special attention. The same batch of material tested at room temperature versus at 65℃ can differ by several times — in summer, a car parked in the sun can easily exceed 60℃ inside, so a good room-temperature report doesn't mean it looks good after baking in the sun. Below is the analytical conditions page of the same report, 65℃ for 2 hours, which readers can compare directly:

The other set is at the vehicle level: the wood flooring for the Denza D9 platform was sent to PONY Testing for six vehicle-grade validations, executed under BYD corporate standard Q/BYDQ-A1901 series. The report numbers, test conditions, results, and conclusions for the six items are listed below — note that for weather resistance, the limit reads "color change grade ≥ grade 3," while the measured gray scale was grade 4-5, a two-grade margin, not just barely passing.

Original reports:PONY Test scratch-resistance report, page 3 (No. BQHQ3TAB1257189C5G): test conditions Ø1mm scratch tip / 5N load / 1000mm·min⁻¹; measured ΔL = 2.85, limit <5.0; conclusion: compliant

Finally, the system certifications. This is the area most prone to merchant exaggeration, so both the certificate numbers and their scope of application are listed together:

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

One verifiable point:In the Guangzhou Xince report (number EGZ2211070005V00104RM1), the test condition was 2 hours of heating at 65°C: formaldehyde measured 1.41 μg/80cm² against a limit of 1.5; acetaldehyde 0.26 against 0.4; toluene 0.08 against 3; acrolein, benzene, styrene and phthalates were all not detected.

These numbers are not decoration for show.Take the numbers and ask the dealer for the originals— if they don't match, or they'll only show you a screenshot with no number, then you needn't listen any further to the "automotive-grade" pitch.

How to verify the test reports a seller claims to have

When a seller says "we've done automotive-grade testing", that statement by itself can't be verified, buta report number can be. Below are five checks that anyone with the number in hand can do:

1. Cross-check the VOC report. Ask the seller for the report number, usually formatted as a testing-lab code plus a string of digits; if you can't get a number,

or they'll only show you a screenshot with no number, then the report most likely can't be relied on. A proper report must include: the full name of the issuing body,

the report number, the standard applied, the test conditions (temperature and duration), and a table with measured values and limits side by side.

One that only reports "pass" without numbers gives you no idea how much margin there is.

2. Look at the test conditions, not the conclusion. For in-cabin VOCs, temperature is key. Data measured at room temperature may look good,

but after summer sun exposure, cabin temperatures easily exceed 60°C, 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. For patents and documents, check the entity. Design patents can be looked up by application number in the National Intellectual Property Administration's patent search system,

where you can see the filing date, applicant and designer. For appearance patents on accessories like those for the Li Auto L9, a difference of a few days in the filing date can mean a completely different outcome,

so when you see "we hold a patent", first check the filing date, then check whether the applicant is actually that company.

4. Check the validity of system certifications. Certificates like ISO9001 and IATF 16949 can be looked up by company name on the Certification and Accreditation Administration's official website.

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.

One common-sense point worth clarifying:a system certification proves the production process is traceable and management is compliant; it does not prove that any given product is durable.

Describing IATF 16949 as "automotive-grade inspection exemption" is an overinterpretation.

5. Verify honors against public listings. High-tech enterprise designations and local industry association awards usually have public lists that can be checked.

The key is to look atthe year and the awarding body, not at photos of trophies — for what awards a company has won over the years,

the record on the public list is more reliable than the marketing materials.

References

1. GB/T 17657-2013 'Test Methods of Physical and Chemical Properties for Wood-based Panels and Decorated Wood-based Panels', National Standard, 2013
2. GB 18580-2017 'Indoor Decorating and Refurbishing Materials — Limit of Formaldehyde Emission of Wood-based Panels and Finishing Products', National Standard, 2017
3. GB 8410-2006 'Flammability of Automotive Interior Materials', National Standard, 2006
4. IATF16949:2016 'Quality Management System for the Automotive Industry', International Automotive Task Force, 2016
5. '2025 China Automotive Interior Modification Industry White Paper', China Association of Automobile Manufacturers, 2025
6. Toyota TSM 0508G-2009 'Testing Specification for Volatile Organic Compounds from Non-metallic Automotive Interior Materials', Toyota Motor Corporation, 2009

Editorial Note

The flooring prices, installation plans, and performance parameters mentioned in this article may vary depending on vehicle configuration, production batch, and workshop processes. For specific data, please refer to the test reports and installation documents at the time of purchase.

If you wish to quote content from this article, please cite the source.

Expert: Sun Zhiqiang, Technical Director of Commercial Vehicle Modification, 15 years in the industry, certified modification technician by the China Automobile Dealers Association