Aluminum, high-strength steel and composites: why repairs cost more

Newer cars use aluminum panels, ultra-high-strength steel and, in a few models, carbon-fiber composites because those materials make a car lighter or stiffer without losing crash protection. The same properties make them harder to fix: many cannot be straightened with a pulling tower or a torch, some need dedicated tools and work areas, and a part that once cost $200 in labor to fix may now be replaced outright. That is part of why repair bills and total loss decisions have moved up, though the effect varies by model and by how the maker designs its repair procedures.

Why carmakers changed the materials

A modern car body is a safety structure first. The passenger compartment is built to resist intrusion in a crash while the front and rear crush zones absorb energy. Making that structure out of mild steel would take more weight; making it out of stronger steel lets engineers use thinner, lighter sections that hold their shape. Aluminum cuts weight further, which helps fuel economy and, in electric vehicles, range. Composites such as carbon-fiber-reinforced plastic have been used where weight is critical.

These are design choices made for performance, and they were not made to raise repair costs. But the repair world was built around mild steel, which is forgiving: a technician could pull a bent panel back toward its shape, apply heat to relieve stress, fill and paint it. Newer materials are chosen for exactly the properties that make that hard. A steel that resists intrusion also resists being pulled back; an aluminum that is light is also more prone to cracking when it is worked.

How the main materials behave in a crash and in the shop

Ultra-high-strength steel

Hot-stamped, boron-alloyed steel is formed red-hot and then quenched, which locks in a very hard structure. Steel suppliers describe it as the material of choice for anti-intrusion parts such as B-pillars and door rings, the posts and frames beside the occupants (ArcelorMittal). That is the property that matters in a side impact. It also changes the repair. In a 2014 article on removing a boron-alloyed reinforcement, I-CAR, the collision repair training organization, noted that the part was so strong that a 10-ton pulling tower had a hard time moving it (I-CAR).

Heat is the other problem. I-CAR's guidance on straightening and heat says several makers publish a repairability matrix showing when heat is allowed, many specify temperature limits by metal type, and heat "can permanently damage certain metals by breaking down the molecular structure that gives it strength and memory" (I-CAR, 2020). Tesla's collision repair procedures, as I-CAR summarized them in 2024, do not allow cold or heat repairs on ultra-high-strength steel at all (I-CAR, 2024). That does not mean every maker bans it; it means the answer is in each maker's manual, and the shop has to look it up for each model.

Aluminum

Aluminum is not "weaker" steel; it is a different metal with different rules. It conducts heat away quickly, so a technician cannot judge temperature by color. Collision-repair guidance from AIA Canada suggests a target of about 250 to 450 degrees Fahrenheit for heat shrinking, staying under 400 degrees because adhesive near the repair starts to break down there, and avoiding about 750 degrees where the metal is permanently softened (AIA Canada). The same piece tells repairers to follow the maker's procedures. In plain terms, a small mistake can ruin the part.

Aluminum also demands a different shop. IIHS wrote in 2015 that aluminum repairs need a separate work area and dedicated tools to avoid steel-aluminum contamination that causes corrosion, and that technicians need training in aluminum welding, riveting and bonding (IIHS). Those requirements are fixed costs the shop recovers through its rates; see our companion article on why labor rates and paint costs differ so much.

Composites

Carbon-fiber-reinforced plastic is the least common of the four and the most counterintuitive. It does not dent; it cracks or delaminates. I-CAR's guide to the BMW i3's carbon-fiber structure explains that damaged carbon-fiber parts are replaced rather than repaired, using BMW's sectioning procedures with defined cut locations, a supplied backing panel and adhesive, and special tools (I-CAR, posted 2014 and validated 2024). The lesson is not that composites are always expensive to fix. Early 2014 press reports said the i3 was cheaper to repair than expected, because a maker that designs sectioning points into the structure can make repair practical. The material alone does not decide the bill; the repair design does.

What actually raises the bill

The materials raise repair costs through four channels:

1. More parts replaced, fewer repaired. When a panel cannot be pulled or heated, replacement is the only compliant option. A new aluminum bed side costs more than hours of labor on a steel one.
2. More labor hours per repair. IIHS found the front repair on its test aluminum F-150 took more labor because mechanics had to assemble wiring harnesses and splash guards under the new fender (figures below).
3. Equipment and training. A shop that does aluminum, calibrates sensors or sections high-strength steel buys welders, riveters, clean rooms, measuring systems and training, then spreads the cost across its rate.
4. Sensors in the structure. Cameras and radar are mounted in bumpers, mirrors and glass. Replacing a part that holds one triggers ADAS calibration, explained in our guide on driver-assistance sensors and the cost of repairs. CCC reported that calibrations appeared on 28.3% of repairable appraisals in 2025, up from 21.8% (Autobody News on CCC's 2026 Crash Course, March 2026).

A real test: the aluminum F-150

The best-documented public comparison is the 2015 IIHS test of the aluminum-body Ford F-150 against the steel 2014 model. IIHS ran two 10 mph low-speed crashes with 15% overlap and had both trucks repaired at a Ford dealership certified for aluminum:

Combined repair costs were 26% higher for the aluminum truck. Labor was 22% higher on the front repair, and parts were 42% higher on the rear, where one side of the aluminum bed had to be replaced while the steel bed could be repaired (IIHS, July 2015).

The story did not stop there. Ford disputed the findings, citing repair data from an independent certification company, and a later Highway Loss Data Institute study of insurance claims reported that the aluminum F-150's claim severity came in about 7% lower than the steel truck's, while claim frequency was about 7% higher, a result the researchers tied partly to Ford's repair strategy and pricing of replacement panels (Repairer Driven News on HLDI, 2019). The 2015 IIHS release cited HLDI's earlier finding that aluminum-intensive vehicles had about 20% higher collision claim severities. The honest summary is that material is one variable and the maker's repair planning is another.

A hypothetical: the same crash on two cars

To see the mechanism with numbers you can check, say two cars of similar value take the same hit on the rear corner. These figures are invented to show the pattern, not market data.

On those assumptions Car 2's bill is nearly four times Car 1's from the same corner hit. If both cars were worth $12,000, neither would be close to a total loss. If Car 2 were a 10-year-old model worth $7,500 and the same crash also bent structure that needed sectioning, it could be.

Materials and total-loss decisions

A total loss decision compares the repair estimate with the car's value. Materials raise the numerator, because replacement parts and slower procedures raise the estimate, but they do nothing for the denominator, because the car's market value depends on age, mileage and demand. An older car with an aluminum hood and an ultra-high-strength structure is therefore more likely to cross the line after a moderate crash than the same-aged steel car. CCC reported that total losses were 23.1% of all claims in 2025 and that the average age of U.S. light vehicles reached 12.8 years (Autobody News on CCC, March 2026), a combination that pushes more claims toward the threshold. Our article on why more cars are being totaled covers that trend, and why EVs are totaled after minor crashes covers the battery-pack variation.

The manufacturer's procedures bind the shop

Shops do not choose repair methods by preference. Makers publish repair procedures and position statements, and I-CAR's bottom line on heat is "always follow OEM procedures." A shop that departs from them can leave a car that crumples differently the next time. That is also why the safety discussion belongs in the claim: if the maker says a part must be replaced, an estimate that quietly repairs it is cheaper and worse.

For you as the owner, this has two practical consequences:

• Ask the shop which procedure it used. A good shop can print the maker's procedure page for the structural operations on your car. Our article on structural and frame damage lists what a proper repair file contains.
• Expect a supplement. Once a car is disassembled the shop often finds damage the first estimate could not see, or finds that a procedure requires an added step. That is normal, not necessarily padding.

Safety versus repair cost

A structure that is hard to repair is not necessarily a flaw. The 2015 F-150 earned high marks in IIHS crash tests, which is the reason the repair costs mattered to the study: strong occupant protection and expensive repairs can coexist. The trade-off for drivers is that the safest structure is sometimes the most expensive to put right, and the cost shows up in claims data and, eventually, in premiums.

How it feeds your insurance rate

Insurers do not price a car by its materials; they price it by what claims on that model cost. Each model is placed in a rating group through a vehicle symbol based on its loss experience, including how often it is claimed on and how much each collision claim costs. The Highway Loss Data Institute publishes model-level loss data that the industry uses; our guide to IIHS and HLDI insurance loss data explains how to read it. A model whose repairs run high shows up as higher collision severity, and its collision rate can reflect that. If a model's repair costs fall, as the later F-150 data suggest they did for that truck, its rating can follow.

The sensible response is to compare quotes for the exact trim before you buy; see check insurance costs before you buy a car.

Questions to ask

• Is the damaged panel steel, high-strength steel, aluminum or something else?
• Does the maker's procedure allow repair, sectioning or heat on this part, or require replacement?
• Is the shop equipped and trained for this material? Is it certified by the maker or a third party?
• What post-repair scans and calibrations are included in the estimate?
• Will I get a copy of the repair procedures and the calibration report?

Common questions

Does an aluminum car always cost more to insure?

No. Insurance cost follows the claims experience of the model, and the F-150 data show it can change. Quotes for the trim you want are the only reliable answer.

Can my local shop repair aluminum or high-strength steel?

Some can, many cannot. The shop needs the right equipment, training and a separated work area for aluminum, and access to the maker's procedures. Ask whether it holds a manufacturer or I-CAR certification, and ask for the procedure.

Why not just use the cheaper aftermarket part?

For structural and safety parts, the maker's procedures and your state's rules govern. For cosmetic parts it may be allowed. See OEM parts for the difference and the state rules, which vary.

Is a repaired structure as safe as a new one?

If it is repaired according to the maker's procedures with the right equipment, the intent is that it performs as designed. If shortcuts were taken, it may not. That is why the procedures and documentation matter.

Key takeaways

• Aluminum, ultra-high-strength steel and composites protect occupants and save weight, but many cannot be pulled or heated, so more parts are replaced and more procedures apply.
• Repair costs depend on the maker's design and procedures as well as the material: IIHS measured a 26% repair premium on the 2015 aluminum F-150, while later HLDI claims data showed lower severity.
• The maker's repair procedures bind the shop; ask which procedure it followed and expect supplements after teardown.
• Higher estimates push older cars toward total-loss thresholds because the car's value does not rise with its materials.
• Insurers price from claims data by model, so quote the exact trim before you buy.