An app that uses a phone’s microphone and accelerometer to diagnose a vehicle’s potential problems. It will enable wannabe mechanics and the safety-conscious, but could also be useful to others. The app relies on the phone’s built-in accelerometer and microphone to monitor the car’s performance and detect signs of malfunction without any special connection—relying instead on the sensitivity of today’s smartphones. By comparing the sounds and vibrations of well-tuned cars to the sounds of specific problems, the app’s machine learning system can detect subtle differences and alert the user to any potential problems. Data combinations are the key to the app’s AI and its ability to diagnose a problem accurately. For example, to determine if tires are overinflated or going bald, the app monitors the phone’s GPS to determine speed. Vibration data is then added to determine how fast the wheels are turning. That can be used to calculate the wheel’s diameter, which can then be compared to the diameter expected if the tire were new and properly inflated. Multiple recordings of sound from the vehicle can be used over time to diagnose further problems as well. A smartphone in the hand, can detect the vehicle’s exhaust note, some pings, and so forth. A phone mounted to the vehicle’s dashboard can do even more. The accuracy of diagnostic results so far better than 90 percent. The app is 100 percent accurate for misfire detection. A scenario where a ride-share passenger who is using the app tells the driver that the car might need a filter change or some new spark plugs. The reality would carry the technology much further, though, as everyday car owners could use it to become more intimately familiar with the nuances of their vehicle and its needs. It would also empower used car buyers.