Noise Car ....Do not purchase

Recently , purchased New Alto Vxi Model Car is worth of price and features. But when you drive the car speed above 50 Found horrible noise , comes from the engine Main thing is that noise spend in the car internal side ..that is my observation and this is true But maruti person says this is normal operating sound...i think new BS6 Alto engin totally fail No any one petrol cars gives Sound Whenever going to purchase this car kindly take test drive first..