Hi, just bought a 17 r4 hybrid . Previously owned a camry hybrid and it was very quiet. When standing by the camry, if the gas engine cut in, you could hardly hear it. When driving the camry, it was also quiet inside the vehicle. When driving the r4, it is noisy. Is this common with the r4 hybrid? When my husband mentioned the noise to a Toyota mechanic, he was told that the noise was to warn people the vehicle was there as other hybrids were too quiet. Otherwise I love the vehicle, but am worried that the noise is a symptom of an engine which is not properly made or tuned.