I have my many, many problems with the Silver Arrows, many of which where brushed on by Ballaban in his Nazi LSR article. But dammit did the W25 Mercedes sound good.
It's got a straight eight with a roots supercharger that blew directly through the engine's two carburetors. They say the car screams, but it's more like an air raid siren. Or like an old firestation that is both ringing its alarm and also being torn down by a large ogre.
Here's one running at the 2013 Klausenpassrennen in the Swiss Alps.