I just bought a 2013 Elantra GLS last weekend. When the engine is running at idle and I'm standing outside of the car, the engine seems to be noisy. Maybe to the point where there is a small exhaust leak somewhere. I don't notice the noise when I'm driving the car - interior noise seems normal. Is it normal for the 1.8L engine to be a bit noisy at idle? The car just turned 100 miles. Thanks!