All modern 4 cylinder engines produce the valve clatter noise. VW/ Audi engines have been doing this for ages.Unless we can find more oil from Mars or the canadian tar sands, or find ways to magically remove or bury all the fossil carbons that we have released from oil into the atmosphere, the days when we lust for the straight 6 cylinder sound is gone for most people.
I guess more people will be shocked or complain when they hear BMW is already coming out with a 3 cylinder 1.5 engine in the 1series ( read Autocar ). I bet this would sound a lot worst heh heh heh

. I can imagine in 5 years time, the next 328i would be poweredby a similar 1.6 engine...and to make that 6 cylinder sound, bmw will rollout the system that makes the synthetic sound from the speakers like what the M5 is doing now into all 3 series.
The upside? We can still have some "joy" and performance from rear wheel drive, 50/50 weight, 242hp, 6.1 secs to the century, all at our disposal while producing less than 150 of CO2 and returing apprx 7.7l/100km (6.3 theoretical is not yet achieved).
Sacrifices...