Brakes, Suspension, and Cooling: The 3 Car Parts That Matter More Than Horsepower
Ask most drivers to name the most important part of their car, and you'll get "the engine" almost every time. It's an understandable answer, and also not really the right one. According to the National Highway Traffic Safety Administration (NHTSA), brake-related issues are identified as the critical pre-crash factor in roughly 22% of crashes where a vehicle defect was found responsible — a bigger factor than most people would guess, and one that has nothing to do with horsepower. This piece covers three systems that get far less attention than the engine, but arguably do more to determine whether a car is actually safe, comfortable, and capable: the brakes, the suspension, and the cooling system.
1. Brakes: The Part Doing More Work Than Your Engine Ever Does
Every time you press the brake pedal, you're triggering a hydraulic chain reaction. The master cylinder converts the mechanical force of your foot into pressure inside the brake fluid, which travels through brake lines to a caliper at each wheel. Inside that caliper, a piston (or several) pushes brake pads against a spinning rotor, and the resulting friction converts your car's kinetic energy into heat — enough heat, in hard braking, to glow visibly on a track day.
That heat is also the entire reason extreme performance cars often use carbon-ceramic brakes instead of the conventional cast-iron rotors found on most cars. Cast iron rotors can suffer from "brake fade" — a temporary loss of stopping power — when they're worked hard repeatedly and can't shed heat fast enough. Carbon-ceramic rotors, built from carbon fiber reinforced with silicon carbide using a manufacturing process that can take around three weeks per rotor, resist that heat far better and weigh roughly 50% less than an equivalent iron rotor, which also reduces unsprung weight and improves how a car rides and handles.
The Rimac Nevera R is a useful real-world example of how seriously this gets taken at the top end of performance: it uses copper-free carbon-ceramic brakes specifically engineered ahead of 2025 regulations in some markets banning copper from brake pad friction material, a change driven by copper's environmental impact when brake dust washes into waterways.
Watch How Carbon-Ceramic Brakes Are Actually Made
Worth watching for the manufacturing detail alone — it's a genuinely different process from stamping out an iron rotor, and it explains why a carbon-ceramic brake package on a road car can cost more than some entire used vehicles.
For practical, everyday maintenance guidance, NHTSA's own vehicle safety resource is a reliable starting point — squealing, grinding, a soft or spongy pedal, or the car pulling to one side under braking are all signs worth having checked promptly rather than waiting for a scheduled service.
2. Suspension: The System Deciding Whether Your Tires Ever Touch the Road
A car's suspension has one job that sounds simple and isn't: keep every tire in consistent contact with the road, no matter what that road is doing underneath it. It does this through springs, which absorb the initial impact of a bump, and dampers (commonly called shocks), which control how quickly the springs are allowed to rebound — without dampers, a car would bounce for several seconds after every pothole instead of settling almost immediately. Control arms, sway bars, and bushings fill in the rest of the geometry, keeping the wheels aligned correctly relative to the road and to each other as the suspension moves.
This is also where the balance between comfort and control gets decided, and it's a genuine trade-off rather than something engineers can simply optimize away. Softer springs and dampers absorb more of the road's imperfections, which is why a plush luxury sedan rides so much more smoothly than a stripped-down track car — but that same softness allows more body roll in corners, sacrificing the precise, connected feeling a stiffer setup delivers. We've seen a genuinely radical solution to this trade-off in the Yangwang U9 Xtreme's DiSus-X system, which uses a LiDAR sensor to read the road roughly 40 milliseconds ahead and adjust each wheel's suspension travel individually, in real time — effectively trying to have both extremes of that trade-off at once, rather than settling for one fixed compromise.
For a car built more for daily transportation than record-chasing, wheel and tire choice directly affects how much work the suspension has to do — a topic we've covered in more depth in our guide to wheels and tires, since a shorter tire sidewall transmits more of the road's imperfections straight into the suspension before the springs and dampers even get a chance to absorb them.
3. Cooling: The Invisible System Every Powertrain Depends On
Whether a car runs on gasoline or electricity, it generates far more heat than most drivers ever think about, and managing that heat is arguably as important to how the car performs as the powertrain itself. A conventional combustion engine's cooling system circulates liquid coolant through passages inside the engine block, carrying heat away to a radiator at the front of the car, where airflow (helped by an electric or belt-driven fan) dissipates it into the atmosphere. A thermostat regulates how much coolant flows, keeping the engine at its ideal operating temperature rather than running too cold or too hot.
Electric vehicles face a related but distinct challenge: their batteries and motors both generate significant heat under load, and unlike a combustion engine that's constantly fed fresh fuel and air, a battery pack has to shed that heat while operating within a fairly narrow temperature range to stay safe and maintain its performance. Most modern EVs use a liquid-cooling loop that circulates coolant through channels built directly into or around the battery pack, often sharing components with the cabin's climate system to improve overall efficiency. This is exactly the kind of engineering problem we ran into repeatedly while covering the fastest EVs on this site: the Yangwang U9 Xtreme's unusual 1,200V electrical architecture exists specifically to reduce how much current — and therefore how much heat — its motors and battery need to handle to produce nearly 3,000 hp without a thermal failure.
The trade-off shows up clearly in sustained high-speed driving, too. It's a meaningful part of why the Bugatti Chiron Super Sport 300+'s independently measured 304.773 mph run — sustained on a combustion engine that can shed heat continuously as long as fuel keeps flowing — remains faster than any electric hypercar we've covered has managed under equivalent independent verification. Battery and motor thermal limits currently make sustaining extreme output for the many seconds a genuine top-speed run requires a harder problem for an EV than for a liquid-cooled engine burning fuel on demand. The U.S. Department of Energy's Alternative Fuels Data Center has more background on how EV battery systems are designed and managed, for readers who want to go deeper on this specifically.
Why These Three Systems Matter More Than a Spec Sheet Number
None of these three systems show up in the numbers most car shopping starts with — horsepower, 0-60 time, or range. But a car with brakes that fade under repeated hard stops, a suspension that can't keep its tires planted, or a cooling system that can't sustain performance for more than a few seconds is a car that can't reliably deliver whatever those headline numbers promise. The fastest, most powerful cars we've covered on this site earn those numbers largely because their engineers treated these three systems as seriously as the engine or motor itself — and the same principle, at a much smaller scale, applies just as much to whatever's parked in your own driveway.
Common Questions
What are the signs that my brakes need attention?
Squealing or grinding noises, a soft or spongy brake pedal, the car pulling to one side when braking, or vibration through the pedal are all common warning signs. NHTSA's vehicle safety resources recommend having any of these checked promptly rather than waiting for a scheduled service interval.
Are carbon-ceramic brakes worth it on a road car?
For most daily drivers, no — they cost dramatically more than conventional brakes and their main advantages (resisting fade under repeated hard use, reduced unsprung weight) matter most on a track, not in daily commuting. They're a genuine advantage on dedicated performance cars and hypercars, where sustained hard braking is a real, repeated scenario.
Why does my car feel stiffer or bouncier than a friend's car of the same size?
Suspension tuning is a deliberate trade-off between comfort and handling control, not a manufacturing inconsistency. A stiffer setup reduces body roll and improves cornering precision at the cost of ride comfort over rough roads; a softer setup does the opposite.
Do electric cars need a cooling system if they don't have an engine?
Yes. EV batteries and motors both generate substantial heat under load and need to stay within a specific temperature range to perform safely and consistently, which is why virtually all modern EVs use a liquid-cooling loop around the battery pack, distinct from — but sometimes connected to — the cabin's climate system.
Why do combustion cars still hold speed records that electric cars haven't matched?
A large part of the answer is thermal: sustaining extreme power output for the length of time a genuine top-speed run requires generates enormous heat, and a combustion engine burning continuously supplied fuel currently manages that heat more easily over sustained periods than a battery and motor system with fixed current and thermal limits.
Read More From This Series
- Rimac Nevera R: 24 World Records, a Guinness Title, and the Most Verified Hypercar Ever Built
- BYD Yangwang U9 Xtreme: The 496 km/h Electric Hypercar That Beat Bugatti
- Bugatti Chiron Super Sport 300+: The 304 MPH Record That Was Never Actually Official
- Tires and Wheels Explained: What Bugatti's 300 MPH Tire Teaches Every Driver
Sources
- National Highway Traffic Safety Administration (nhtsa.gov) — vehicle safety and brake maintenance guidance, brake-related crash-factor data
- U.S. Department of Energy, Alternative Fuels Data Center (afdc.energy.gov) — electric vehicle battery and thermal system background
- Motor1.com, "Carbon-Ceramic Brakes Explained" — carbon-ceramic manufacturing process and performance trade-offs
- Engineering Explained (YouTube), sponsored feature on carbon-ceramic brake manufacturing and cost
- HowACarWorks.com — braking system and hydraulic circuit fundamentals
- HowStuffWorks.com — brake caliper and disc-brake mechanical operation
- Our own previously published coverage of the Rimac Nevera R, Yangwang U9 Xtreme, Bugatti Chiron Super Sport 300+, and our wheels-and-tires guide, linked throughout
