The 0-60 mph is something you will certainly see on the brochure of pretty much any new car on sale or even the classics. Most times, vehicle maximum speed (V-Max) is also the same.
We’re in a day and age where a single gram of CO2 in emissions can be a defining factor in the saleability or profitability of a vehicle. So is if the competitors reach 60 mph fraction of a second quicker - stakes are high.
But reaching a higher V-Max means also a bigger burden on the brakes to stop the car safely and in a limited time / distance travelled. A higher V-Max will very quickly show itself in various vehicle attributes and specifications such as weight, emissions, aerodynamic performance, drag, etc. All of these are key inputs to the way a vehicle is designed and engineered.
Vehicle brake systems can define many factors, or at least heavily influence their balance in the overall design of a vehicle. The sizing of the brake system defines the minimum wheel size. The braking power might restrict the V-max of the vehicle. The cooling required for the brake system might define the A-class surface of the vehicle - and not only the front of it. Towing might be limited if the vehicle can’t stop. And once you put all of this into perspective, the brake system is in the middle of the definition of the vehicle and its capabilities and competitiveness. All of this, combined with the substantial cost of development and testing of various configurations of a vehicle shows how eventually braking capability of a vehicle can define what’s designed, engineered and sold.
Some manufacturers are capping their V-max to the highest speed limits in the markets, and not to what the car can achieve in the Autobahn. This means smaller brakes can serve the car just fine, the car is lighter, less emission, less environmental impact, and less engineering cost and time as fewer brake sizes (or just one size) might cater for requirements of the vehicle just fine. However, if the higher trims of a vehicle will need to be able to achieve a certain maximum speed, this might mean additional higher performance brake systems, as well as other functional parts and systems in the vehicle.
Depending on the vehicle size / segment and the target market, the move to capping the V-Max might not necessarily impact the profitability of the vehicle but yet substantially safe on the resources such as initial investment towards the product and the associated environmental impact of it.
Dr Mo Esgandari has over a decade of experience in Brake NVH research & development and has published in various academic journals. Mo also has a comprehensive hands-on automotive design and engineering experience delivering various vehicle programmes. Mo is one of the instructors on Brake Academy.