The AMG 300SL vs SLS Black Series

The Rumpler Tropfenwagen was the first car to use a swing rear axle. That was in 1921, which was pretty good going for what was effectively an independent suspension set-up.

The Mercedes 300SL ‘Gullwing' is better known than the Rumpler - as are most things, to be fair - a lot faster, and also has a swing rear axle. Anyone who's ever driven one quickly on an undulating road will, once they've had a long sit down and a stiff drink, tell you that high speeds and sudden camber changes can make the Gullwing officially ‘interesting'. Even Stirling Moss admitted as much to me once, and he knew what he was doing.

The 300SL you see here gets round this problem by junking the original suspension and replacing it with the rear set-up from its late-'80s SL successor. It also has AMG's 6.0-litre ‘M119' V8, good for around 380bhp and previously best enjoyed in the über-rare mid-'90s AMG SL60, a four-speed automatic transmission, adjustable Bilstein dampers, and proper brakes. You no longer need to imagine what a 300SL Gullwing fettled by AMG might be like, because this is it.

In fact, should you have £600-800k lying around, you could own it - the AMG 300SL is one of the more intriguing lots at this weekend's RM Auctions' Monaco event. So intriguing, in fact, that TG.com asked if we could have a go, and were rather surprised when the man on the phone said yes. It also seemed like a good excuse to bid a proper farewell to the other notable AMG with gullwing doors, the SLS, pumped up to borderline race-spec in Black Series mode.

Remember, that was the car that almost stole the show during last year's Speed Week, and on the way to our rendezvous with the SL, its insane pace and unreconstructed character is as addictive as ever. On a dry road, and with its Michelin Cup tyres on song, the SLS Black manages to be eye-poppingly exciting and a reminder that not all of the class of 2014 supercars makes things easy. This is an old-school handful, partly because it's so wide and low, partly because it has 622bhp and is perfectly prepared to introduce you to each of them personally. Even at a thumping £230k, I reckon that while regular SLS values haven't levelled out yet, the Black Series is a copper-bottomed blue-chip future classic investment. Not least because there aren't very many of them...

There are 1400 300SL Gullwings. I've driven one. Its racing genealogy - it was closely related to Mercedes' epic early 1950s competition cars - brilliantly barmy doors, and the fact that it was the world's fastest production car at the time, and the first to use fuel injection, all underpin its rep as a true legend. Hugely valuable now, too, but it's best to ignore that while you're driving it. The L in SL stands for ‘Leicht', and the 300SL is indeed intoxicatingly nimble and light.

This AMG version turns out to be something of a conundrum. Technically, this is a 1954 car, but so much has been changed your expectations are swiftly all over the place. It's one of only 11 made, between 1996 and 2009, five of which were commissioned by the Sultan of Brunei. The tubular steel chassis is mostly intact, and the body is identical to the original car. With its elongated bonnet and wheel arch brows, it looks as marvellous as ever, bar the '90s-era AMG alloys which fit the car's lissom form as smoothly as double-glazing fits on a medieval castle.

The red leather-trimmed cabin is also, how can I put this, a matter of taste. It's not to mine, but the interior quality is still mesmerising, with slivers of aluminium on the door handles, air vents and switchgear. The original car had a skinny wheel that folded out of the way to allow for easier ingress and egress over those fat sills (that's why the car ended up with those gullwing doors). This one has a modern airbagged job, which runs the alloy wheels close for jarring inappropriateness. The gear selector surround is also '90s-era Merc, parachuting a hint of Stuttgart taxi into the rarefied 300SL ambience. Oh well.

Detail quibbling takes a walk the second you fire it up. If you're lamenting contemporary AMG's turbo embrace versus normally aspirated, thumping big V8s, then this one's for you. It idles with a plump baritone warble, and if you squeeze the wonderfully heavy throttle pedal it hardens into a serrated growl loud enough to be heard in the SLS's cabin - and the Black Series is hardly a wallflower.

This particular car has done barely 350 miles, so a full road test is not on the cards. But it thunders forwards exactly like all the 1990s AMGs I've ever driven, and is immediately more useable than the original car, simply because it handles and stops like a late-20th century car rather than a mid-century one. Modern Michelin rubber obviously transforms it too, although it's difficult not to feel nostalgic for the original's six-cylinder scream and delicacy, challenging or not.

As automotive mash-ups go, this one has unimpeachable pedigree. Along with the Eagle Low Drag E-type - which costs almost identical money to the AMG 300SL - it's proof that the resto-mod is one of the car world's more intriguing avenues. Which begs the question - if you could upgrade a classic with modern hardware, what would it be?

Thanks to RM Auctions and Universal Classic cars. Follow the AMG 300SL's progress at the Monaco auction this weekend (May 10th). Or better still, bid for it.

Photos: Rowan Horncastle