Even the sound of the newer engines is reduced. Common-rail fuel injection reduces injector noise, which is most of that rattle you hear. The emissions equipm

Even the sound of the newer engines is reduced. Common-rail fuel injection reduces injector noise, which is most of that rattle you hear. The emissions equipment muffles the exhaust a bit. Even valve noise is reduced because they need to control things to finer tolerances. But a big diesel will always sound a bit beefy I think. The smaller 4-cylinders shouldn't be discernable from gas at all.