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Tesla Model 3 cost-savings show up in places most buyers never see — underbody panels, small fasteners, and bracket choices that add up across hundreds of thousands of units. In a recent Munro hoist review, the team highlighted seemingly minor changes that compound into meaningful savings in parts, labor, and weight.
For automotive engineers, EV enthusiasts, and investors, these observations underscore how disciplined, continuous improvement turns pennies per car into six-figure gains over a program’s life.
Snap fits done right — and why that matters
Most OEMs struggle with snap fits. Poorly designed features rattle, loosen, or crack during service. On this Model 3, the access cover’s snap-fit execution is tight and precise. The audible snap signals robust retention; the interface sits flush, and the geometry separates the load path between the air shield and the lower panel.
That separation is smart engineering — it keeps fastening load localized, reduces stress concentration, and supports serviceability because a tech can remove one piece without disturbing a larger assembly. Good snap fits reduce screw count, cycle time, and mistake-proofing overhead. They also lower total cost by cutting fastener variance and eliminating thread‑forming operations.
Variant management without line chaos
The rear fascia shows an access cover aligned with a European towing variant, even though the North American car lacks a tow package. At first glance, that looks like waste. The tradeoff is more nuanced. Global architectures juggle content differences while maintaining line takt. Sometimes it is cheaper — and more reliable — to standardize a cutout and cover than to manage two bumper mold variants, two supply streams, two inventories, and additional changeovers.
The right answer depends on volumes, tool amortization, and defect risk. If the cover’s cost exceeds the overhead of variant management, delete it. If not, a single global fascia with a well‑integrated closure can be the leaner path. The point is systemic thinking: minimize complexity at the constraint, not just at the part.
Weldments versus tubes — simplifying the five‑link
Under the car, one link in the five‑bar rear suspension mirrors the Model Y approach: a welded fabrication replaces prior tube‑based pieces. Weldments consolidate operations and allow tighter control of bracket and bushing locations without expensive machining. With a capable supplier, they deliver repeatable geometry and lower scrap risk. They also open design options — plate thickness and gusset shape tune stiffness and NVH more easily than with fixed‑diameter tubing.
For teardown analysts, this screams cost‑down through process selection: choose a manufacturing route that meets tolerance with fewer steps.
The myth of missing nuts — and the reality of disciplined build
Internet lore loves a dramatic failure. However, in this case, the hoist check found upper and lower control arm hardware fully present and properly finished. That discovery matters for two reasons. First, it confirms Tesla’s maturing process control on safety-critical joints. Second, and just as important, it shows how sampling should work in teardowns: verify, don’t assume.
In other words, while quality perception often starts with closures and paint, real engineering quality lives in the joints, torques, and corrosion protection under the car.
Deleting studs and push nuts — the anatomy of a penny
Small hardware vanishes on this Model 3: four welded studs, matching push nuts, and a pair of push pins that once held a minor tab are gone. The distance between features made the extra retention redundant. Deleting them saves parts, weld time, handling, and error opportunities.
By Munro’s rough math, that set of deletions saves about $0.17 per car in material and labor. On 400,000 units per year, that’s $68,000 — roughly a free car. Over a five‑year run, $340,000. Critics might wave that off as noise. They miss the manufacturing truth: vehicles ship with tens of thousands of parts. If you harvest $0.17 a dozen times a quarter across ten subsystems, you stack millions in avoided cost — all while trimming weight and improving serviceability.
Why tiny savings move big needles
Engine programs live or die by cumulative deltas. Every 100 grams removed helps aero, ride, and noise. Every fastener deleted removes a potential cross‑thread, a torque error, or a rattle. Each second cut from station time lifts line capacity or reduces overtime. Finance sees the compound effect; warranty sees fewer defects; customers feel quieter cabins and tighter fits.
Lean design is not a slogan — it is the disciplined removal of parts that do not carry function. The Model 3 examples fit that playbook: remove studs that don’t add retention; eliminate push nuts that don’t add robustness; prefer a weldment if it reduces steps while holding tolerance.
Design for Assembly — practical checks you can steal
If you build EVs or major subsystems, you can apply the same lens:
- Challenge every fastener. Ask what function it carries, what failure mode it prevents, and whether geometry, snap fits, or adhesives can replace it with fewer steps.
- Localize load paths. Separate cosmetic panels from structural shields so service access does not cascade into multi‑panel removals.
- Favor consolidated processes. If a weldment replaces tube cut, cope, drill, and notch steps — and holds bushing centers — you likely reduce cost and scrap.
- Align to the constraint. Delete part variants that create bottlenecks; accept them where tooling amortization wins. Manage complexity where it least harms takt.
- Quantify pennies. Put a number on each deletion — part cost, cycle time, rework probability. Roll it across annual volume and program life. Small bets, big returns.
Cost modeling — beyond the BOM price
The $0.17 story illustrates a complete cost view. Parts cost is step one. Real savings also include:
- Weld cell time: Fewer studs mean fewer load/unload motions and less spatter cleanup.
- Error proofing: No studs, no wrong‑stud Poka‑Yoke, no torque audits for matching nuts.
- Inventory touches: One less SKU to count, store, pick, kit, and reconcile.
- Quality fallout: Each attachment point is a potential squeak, leak, or loose‑fit claim. Remove the point, remove the failure mode.
- Weight and aero: Deleted hardware is small individually; aggregated across the underbody, it cuts drag with smoother panels and fewer discontinuities.
This total‑landed‑cost logic is how lean manufacturing turns design intent into margin.
Continuous improvement — the speed advantage
A clear cultural difference emerges in how quickly changes gain approval. Many legacy OEMs struggle to push even minor deletions through change boards within a single model year. By contrast, Tesla implements small, validated changes in near-real time. This rapid pace matters. It captures savings sooner, compounds lessons faster, and eliminates the “hidden factory” that builds around outdated parts.
The lesson for automakers is direct and actionable. Shorten the loop from observation to approved change. Support every decision with solid data, run pilots on limited builds, and scale quickly once field results confirm success.
What this means for the EV race
EV leaders will separate themselves in quiet places — the undertray, the bracket, the clip. Battery breakthroughs get headlines. Underbody discipline earns profits. The Model 3 updates show a company still mining its own design for waste, even as the platform matures.
That mindset — expert teardown, sharp analysis, relentless cost breakdown — is how you fund bigger bets in cells, motors, and power electronics without sacrificing price competitiveness.
Explore more with Munro
If you want deeper teardown insights, keep an eye on Munro’s expert reviews and cost analyses or subscribe to Munro Live. We dissect fasteners and weldments with the same rigor we apply to inverters, packs, and motors — because lean design starts at the smallest interface. For OEM teams, suppliers, and serious enthusiasts, those details are where margin — and engineering excellence — is won.
Dive into more teardowns, cost breakdowns, and lean manufacturing reviews to see how incremental decisions shape the vehicles that win the EV market.