Guys, just to keep things in perspective, a 3 db difference in sound is classified as "barely perceptible". My stereo at home has a volume knob with decibels and I can say that I need to turn the knob at least a good 5-6 db for the sound to be clearly louder.
Technically, a sound that is 3 db louder than another sound has 2x more "energy" (amplitude), but because of the way our ears perceive sounds (psycho-acoustics), a doubling of the energy results in a sound that is perceived as barely louder:
- Imperceptible Change 1dB
- Barely Perceptible Change 3dB
- Clearly Noticeable Change 5dB
- About Twice as Loud 10dB
So, C&D measured the BMW M2's SPL@70 mpg as 72 db. For comparison:
- BMW M2: 72 db
- BMW 340i: 70 db
- MB E350 (2014): 68 db
(These figures are all from C&D's instrument tests.)
So, the M2 is "barely louder" than a 340i, and the 340 itself is "barely louder" than a luxo-barge E350. Based on this, it seems to be that we don't need to be too concerned that the M2 will be a loud car on the highway.
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