Is your car vibrating when idle? Here's when you should be worried Why Does My Car Shake When Idle? Top Reasons and DIY Fixes Engine shaking while idling? That small vibration is usually worn engine mountsand it only gets worse with time. Left too long, it can lead to extra strain on your engine, gearbox, and even your What Causes Your Car to Vibrate While Idling? 2015 car vibrating at idle, RPM 500 WHY YOUR CAR SHAKES WHEN IDLING If your car feels smooth while driving but starts vibrating or shaking at a stoplight, something isn't right. At idle, the engine runs at its