Both cars still exist, owned by Mercedes. And while Caracciola’s car is a museum piece, Lang’s is kept in perfect working condition, and today it is my honour to drive it. Before arriving, I was convinced it would be for a few slow laps because the car is entirely original: those pistons and conrods are those that powered Lang over the line almost 76 years ago. But that's not the way it turns out.  Because the car is old and has a small engine I’d not taken it too seriously until I realised said engine still produces 275bhp and provides the W165 with the power to weight ratio of a new Porsche 911 GT3. The mild apprehension this causes soon turns to something closer to terror when I realise the accelerator and brake are the wrong way around.  Even worse is a gear shift that places second and fourth where you’d expect to find fourth and sixth. So if you change down normally from fifth you get second and destroy the engine. Changing up from third to where you’d expect to find fourth has the same effect. But if that makes the car sound hard to drive, it’s about to get harder still.  “Don’t drive slowly or it will overheat,” says Gert Straub from Mercedes-Benz Classic. “It will also oil its plugs so we will have to change them all before it will run again.” So I have to drive it fast? “That is correct. And when you drive away, spin the wheels – it is kinder to the clutch.”  In that moment faced with a Grand Prix car of incalculable value that appears impossible to drive, I’d have been happy to run away. And then they fire it up and whatever crumbs of comfort are left in my head are blown to oblivion by a rasping, menacing and deafening howl.  I drop the clutch and with a curl of smoke off each rear tyre, we join the circuit. I can’t recall having ever concentrated harder: one slip of hand or foot will throw the contents of this engine all over the track. I must keep the revs above 4,000rpm to keep the plugs clean and must change gear at 7,500rpm, which seems an insane speed for an original, pre-war engine. But I do as I’m bade and the W165 responds in kind, whooping, screaming and shrieking its way around the track. Surprisingly the steering is a delight and the drum brakes strong, so at least those fears are allayed.
Lewis Hamilton's Mercedes was the F1 car to have in 2014, but 75 years ago one of its predecessors was even more dominant. Andrew Frankel drives it