Driving the world's most expensive car: €135m Mercedes 300 SLR Coupe in the Mille Miglia

Their test figures for it included an average maximum of 176.47mph and acceleration from 0-60mph in 6.8sec and 0-100mph in 13.6sec. Doesn’t sound too stellar today, does it? But this was more than a half century ago… More significantly, it punched itself from 50-70mph in 2.5secs, 60-80mph in 3.1, and 80-100mph in 4.8. It really was an absolute rocket ship, and in period absolutely the world’s fastest road car.

So digest that stature – backed by the unbeatable racing provenance of the 1955-season 300 SLR roadsters (winning the Mille Miglia, the EifelRennen, the Swedish Sports Car Grand Prix, RAC TT and Targa Florio, and being withdrawn post-accident at Le Mans when running first and second) and what do you have? As one leading classic car dealer gasped – “God Almighty! If it ever became available, I’d be confident of serious interest from several players at 50-60 million dollars…”. In other words, ‘The Uhlenhaut Coupe’ is a candidate for being the world’s most valuable motor car.

And I found myself let loose in it. But I’m happy to report that ‘Red’ and I both survived, unscathed. I suspect my companion in the car, Gert Straub, was not so confident. He has cared for the Museum cars for years. He’s a fourth-generation Daimler employee; his father Horst rode with ‘Taffy’ von Trips in a works 3005L during the 1956 Mille Miglia. It was horribly wet, and Trips drove like a man on a mission before crashing heavily. He and Horst Straub escaped serious injury, but the car was destroyed. Did his father express an opinion on Trips’s driving? “Ja. He told me Trips woss total nuts!”.

Now Gert fussed around ‘Red’ like a mother hen, telling me he had been concerned by “a noise in the back axle”. I got the message. “It’s OK, Gert – I’ll treat her like cut glass”. He nodded, clearly unconvinced. He removed the hatch in the driver’s door sill, connected the battery within, then released the steering wheel lock and slid the four-spoked wood-rim from its splines. Sliding down into the driver’s seat he reached across to the magneto switches, click-click, further across for the ignition key – on – push in for the electric fuel pump. An insistent whine from the tank-filled boot primed the Bosch fuel injection – then Gert pressed the starter button on the left of the dash panel. Down below that long, shapely bonnet the 3-litre straight-eight engine began to clash over, chassis shuddering. I pictured those eight pistons shuttling virtually from side-to-side in their cylinders since they are canted at just 33 degrees from the horizontal to minimise centre-of-gravity height.

Cough — ker-BLAAAAAMMMM! Now when I described years ago what the V16 BRM was like to drive, one reader criticised my trying to spell “infantile mouth noises”. Well, please accept my apologies, but I’m at it again. Incredible, cacophonous, car-splitting noise is what the 300 SLR is all about. Conventional language just doesn’t express it. When he tested the sister Coupe in 1956, Gordon Wilkins wrote: “…as soon as one touches the starter button there is a shattering noise from the engine which momentarily numbs the senses. It is compounded by the whine of the gears, the clatter of the desmodromic valve gear and the injection pump, and a variety of grinding noises from the vicinity of the clutch housing…”.

The ensemble settles down into a thunderous warm-up at 3000rpm — Gert occasionally whooping it to 4000. Once warmed through, he switches it off. Silence reigns. We roll the car around the end of the shops and line it up beside the main road, ready to join the Retro pack as they career by. A small admiring crowd gathers. One asks, in English “Is this…” — a reverential intake of breath — “…the Uhlenhaut Coupe?”

We’ve only run a few hundred metres and suddenly we’re being directed left into a village road leading to a major control and lunch stop. Below about 2000rpm the Coupe’s brake booster scarcely works at all. We haven’t yet run far enough to warm the all-inboard drum brakes. Stone-cold — well.. .there aren’t any! None at all. Oh, great… I’ve only driven this legend for a minute, and now I’m about to mow down the packed pedestrian tifosi blocking our path. Neutral, thumb the horn, blip the throttle. WHAAAAAMMMM!!! Good-oh — that worked, they scatter. Now I can coast down, brush in the brakes and — yes — they bring us to rest. Switch off. Well, that’s the first five minutes. Pull the door releases, raise the gullwing… and already my ears are ringing.

When one of the Uhlenhaut Coupes appears, owners of production 300 SL ‘Gullwings’ often come up and say “I’ve got one just like that”. Many of Mercedes’ old boys have given up putting them right. But ‘Red’ and ‘Blue’ are cars of totally superior stature. The SLR Coupe uses a multi-tubular spaceframe chassis in 25mm diameter steel tube. The lengthy engine is slung on two mounting points up front and a rigid sandwich plate at the rear which clamps between the crankcase and clutch housing to the left, and picks up on the cylinder head and cam covers to the right. It’s clearly visible within the cockpit, bolted through the bulkhead. The clutch is offset 8in left of centreline, and the propshaft runs aft into the rear-mounted transaxle’s input at 4 3/4in left of centre. The gearbox internals, drum brakes and suspension parts are effectively common with the sister W196 Formula 1 cars.

While the Grand Prix cars used 2 1/2-litre M196 engines with two four-cylinder blocks within welded-on steel water jackets, the 3-litre M196.I sports car engine features two cast four-cylinder alloy blocks with integral water jacketing. With 2mm greater bore and stroke than the F1 engine, 78mm x 78mm, it displaces 2982cc.

Crank configuration and firing order differed from F1 to sports car unit, while the sports car engine’s valves were set at a wider included angle than the F1 unit’s, and deeper-skirted pistons prevented skewing in the bores. The upstream fuel injection nozzling was improved, and an altitude compensation diaphragm added to the Bosch pump-cum-metering unit to cater for mountain passes on the Mille Miglia and the planned Carrera PanAmericana.

The luscious body style was designed by Karl Wilfert and his colleagues at D-B Sindelfingen. The Coupes, tailored for Le Mans and the Carrera, drew more from the Formula 1 streamliner form than from the open SLR roadsters. The open roadsters were then preferred for Le Mans, while of course that year’s Carrera, in which Moss should again have been navigated by Jenks, was cancelled. Meanwhile, ‘Blue’, the first Coupe, was completed post-Le Mans, before the 1955 Swedish race at Kristianstad. This fantastic car was driven on the road to Sweden and used there as a practice hack. In September ‘Taffy’ von Trips joined the team for the TT at Dundrod in Ulster. To give him experience of the SLR he was issued with ‘0007’ to drive from Unterturkheim to Belfast on the open road. Again ‘Blue’ was used there only in practice.

The pair of Coupes were then stored for some 30 years. Their glorious magnesium-alloy bodies being attached to spidery aluminium body frames by hundreds of ground-flat rivets, age-fracture cracking afflicted both bodies. ‘Red’ seems to have suffered worse. In 1987 both doors had to be re-skinned, while its broken side windows and cracked windscreen had to be replaced.

I slither back in — clunk-click, furl the gullwing doors — “OK” calls Gert, and I restart the sound machine. Back out onto the Retro route, bound for Siena and beyond. As ‘Red’ warmed through, drum brakes, dampers, tyres (and driver) all warmed up and I could appreciate what a fabulous Mille Miglia car her open roadster sisters must have been. The view forward includes surprisingly little bonnet, though the roll and swoop of the multi-curved panelling provides the classic perspective, with the injection intake trunk forming high ground to the right. Ducking down into a winding essbend I get a sense of how the greats — Moss, Fangio, Kling, Herrmann — could have placed the car. Fangio always maintained he couldn’t place a sports car or Formula 1 streamliner as precisely as he could the open-wheelers. Nah — c’mon Juan, what’s your problem? I found the front end grip utterly reassuring. And then Gordon Wilkins wrote “…the Daimler-Benz engineers have produced a car which has almost unbelievable traction and an amazing disinclination to spin its wheels no matter how vigorously the throttle is used…”. And flooring the throttle just powers the tail round to suit. Moss told me how the SLR looks big in photographs, smaller in the metal and feels smaller still from the driver’s seat. Spot on. Given half a chance I’d have loved to press it on the twists of the Radicofani and Futa Passes, but as far as I drove that day it felt just tailor-made to do real racing damage on real roads.

“With such fantastic acceleration, overtaking is possible where one would never normally dream of it”

Again it’s hard to improve on Gordon’s 1956 description: “With such fantastic acceleration on tap, overtaking is possible on short stretches of road where one would never normally dream of it. A quick snatch to pull the gearlever into second, a quick flick on the steering wheel, and the car ahead is overtaken.., where vision permits the car will go rocketing past six or eight others, roaring up to 75mph in second before slowing to a crawl under the action of its fabulous brakes…”. Once warmed through and with the booster awakened they are good too.

Then there’s a grand entry to be made into the mediaeval central square at Siena. The massed crowds there have had a diet of BMW 328s, pre-war rumblies and various adenoidal Italian etceterini with flatulent Fiat power. The occasional serious Ferrari has raised a cheer, but then they must have heard something approaching through the old city’s canyoned streets which absolutely raised the roof.

Now, it’s hard not to enjoy a huge helping of Olympic free-style posing, but to conduct ‘The Uhlenhaut Coupe’ into a Mille Miglia-primed Siena just about takes the biscuit. Yet it’s embarrassing, too; as if I’ve pulled the most gorgeous girl, taken her to a sophisticated dinner and only then discovered how outrageously noisy she can be. In the tight, undulating streets and stop-start traffic, I daren’t slip ‘Red’s clutch. I can only select neutral, toe the brakes, maintain the revs — WHAAAMMM-BLAAAMMM!!! — and wince at the echoes. It’s as if my drop-dead gorgeous girl has studied the Michelin three-star Quenelle de Brochet set before her and bawled at the maitre d’hotel “Oy, gar-kon — Tomater Ketchup perlease!”. Round another corner, again we stop on an up-slope — neutral, brakes, “WHAAMMM-BLAAMMM!” Oh Gawd, now my date has just demanded a side order of pickled onions… and a Bacardi and Red Bull. This beauty is really feisty — a true-born Racer…

And my oh my, what a drive. I have always adored the hard, crisply-defined rap and crackle of a real works racing engine, and when it’s as throaty and full-bodied as the 300 SLR’s the din is an experience to savour. After a memorable run in Uhlenhaut’s last SLR Coupe my brain’s still buzzing. Believe me, the legend of the world’s most valuable race-bred GT car does not in any way exaggerate. As I said to the Editor when he telephoned upon my return home… “Eh? — sorry, can’t hear a word”. That’s the way it was, after a few hours with such an unutterably ravishing — yet embarrassing-to-be-with — total beauty.