By Matt Crisara
Here鈥檚 what you鈥檒l learn reading this story. Xiaomi鈥檚 YU7 SUV was recently seen at a track day suffering a brake fire.This isn鈥檛 the first time Xiaomi has had issues with brakes鈥攖hough the previous instance was a brake failure.Xiaomi isn鈥檛 the only EV manufacturer struggling with brake troubles. A Tesla Model S Plaid experienced total brake failure a couple of years ago and ended up running into the wall.It鈥檚 no surprise that the race track demands the maximum amount of performance any car can provide. This could potentially over-stress safety-critical components that are designed to cope with the demands of daily driving. Your brakes are often the first thing to play up at the racetrack, as many of the components are unable to handle the thermal demands of repeated hard-braking moments that come with track driving鈥攁s evidenced by a brake fire suffered by Chinese maufacturer Xiaomi鈥檚 YU7 SUV in a video from a recent spin around the track. Track-driving enthusiasts鈥攚ho also daily drive their vehicles鈥攚ill upgrade to stainless steel brake lines and higher-boiling-point brake fluid, along with high-performance brake rotors and brake pads to handle the extra demands.But is it normal for them to catch on fire?Possible IssueBefore we get any further, it鈥檚 important to note that the YU7鈥檚 driver forgot one of the cardinal rules of track-day driving. The cooldown lap. It鈥檚 so important that cooldown laps are actually mandatory at many track days you鈥檒l attend. Meanwhile, the driver in the video steams into the pits and wonders why his brakes were engulfed in flames. Learn from his mistakes.The incident also highlights larger issues at play with EV design, namely getting a heavier car around the track successfully鈥攅specially bringing it to a stop. In fact, Xiaomi itself has warned that its YU7 SUV isn鈥檛 designed for track use in its stock form. Most road vehicles have brake pads made of NAO (non-asbestos organic) or low-metallic ceramic formulas, which are designed exclusively for daily driving conditions; these pads are rated for temperatures up to 400 degrees Celsius, but can experience brake fade and even failure as they continue to heat up. Conveniently, the video (see above) includes an infrared thermometer that shows the brake pads registering over 600 degrees Celsius. Despite the obvious thermal issues at play, Xiaomi claims the car wasn鈥檛 in the correct driving mode and therefore didn鈥檛 have its regenerative braking system activated to help slow the vehicle. Regenerative braking slows the car down by briefly allowing the electric motors to act as generators when you let off the accelerator pedal; the Chinese automaker says this could provide up to .2 G of deceleration. For context, Volkswagen鈥檚 latest Golf R hot hatchback鈥檚 automatic emergency braking technology produces a maximum of 0.6 Gs of deceleration. Having driven the Mk8 Golf R myself, I can confirm that it stops incredibly well. Our Experience Driving Performance SUVsWe should note that Xiaomi is no stranger to track driving, as it recently set a new production EV lap record at the N眉rburgring Nordschleife with its SU7 sedan. Unfortunately, the YU7 doesn鈥檛 have quite the same racing pedigree, weighing between 4,718 and 5,423 pounds, depending on the chosen specification. Despite the curb weight, it appears that all YU7 models arrive from the factory with four-piston Brembo brake calipers paired with ventilated rotors.While we haven鈥檛 had the chance to drive a YU7 ourselves, Lamborghini鈥檚 Urus SE is the closest thing we鈥檝e driven. With hybrid systems on board, it weighs a whopping 5,523 lbs. However, unlike Xiaomi, which paired its SUV with off-the-shelf components, Lamborghini armed its Urus SE with the biggest brakes ever fitted to a production car. They鈥檙e made of carbon ceramic material to improve high-temperature performance, and they鈥檙e massive. For context, the rotors at the front axle are 17.3 inches in diameter (accompanied by a 10-piston caliper) while the rear brakes measure 14.5 inches with a single-piston caliper. We weren鈥檛 able to take the Urus to the track, but I can say with confidence that I had more than enough stopping power for spirited driving on backroads. At maximum performance, the Urus can slow from 62 mph to a dead stop in just 36.6 yards. And we think that says it all. Previous IncidentsThe keen among you will know that this isn鈥檛 the first time Xiaomi has experienced issues with its brakes. However, it appears that the latest problems aren鈥檛 related to the other incidents where the brand鈥檚 SU7 experienced complete brake failure. It appears those incidents were a result of pushing components designed for everyday driving conditions well past their comfort zone. The YU7 Max that experienced the brake fire was fitted with higher-specification brake pads and rotors designed for track use.As the incident happened mere days ago, its unclear how Xiaomi will remedy the situation. We have a feeling this one will require more than just an over-the-air update to fix.