Up-To-Date Noise Reduction, E.G., on the New Db 190d

In Autumn 1983, Daimler-Benz launched the world's first fully-noise-encapsulated Diesel car, in the form of the 190D. During its development, priority was given not only to compliance with the stricter legal noise limits which are to be implemented ~ the 190D would manage that even without any special features ~ but also to the desire to make the car noticeably quieter than any of its rivals, both inside and out, and at any engine speed.

The result is a car with body-mounted engine-compartment encapsulation which completely seals off the engine/gearbox assembly from outside, apart from a few air intake and outlet apertures. This cuts down noise emission by about 4-5 dB(A): following the procedures laid down in EEC Directive 81/334, noise levels of 75/73/71 dB(A) were recorded, depending on the type of gearbox fitted. Noise emission at tickover is under 50 dB(A) in all cases. The typical knocking noise of a diesel is now scarcely discernible. Particular attention was also paid to the increased weight, higher engine-compartment temperatures, and the cost. The resultant compromise can be seen ~ or rather, heard ~ to be a thoroughly respectable one