Mercedes Enthusiast – Pure Sport. Specialist unleashes roadster’s wild side

Built by the SL Shop, the 300SL SportLine seeks to entertain the driver like no other R107 – we head to Wales to find out if the roadster delivers the goods.

South Wales’ A4069 is a well-trodden path for the UK’s driving and indeed riding enthusiasts. Situated on the western edge of the Brecon Beacons National Park, this 16-mile roller coaster is the binding link between villages Gwaun-Cae-Gurwen and Llangadog, and claims not just free roaming sheep, but wild horses too on its most spectacular stretch, which ebbs and flows with the landscape and serves everything from switchback hairpins to cambered corners, the vast majority of which are well sighted and wholly inviting. Even to those who have driven some of the best roads in the world, the A4069 still has raw appeal.

With the new day sun yet to flare on the horizon, we have the Mountain Road to ourselves. Crisp morning frost gamely clings to surrounding grassland, and there’s a glass like sheen on the road, reminding me to treat my environment – and my conveyance’s throttle pedal – with respect. The Mercedes-Benz I’m driving wears the body of a 40-year old R107SL, but its vital organ sings for attention like never before, and the car now holds cornering lines like a powerful 400m springer, leading me to believe it is truly on my side rather than simply putting up with my company. Take liberties with these old Mercs in standard form and they can teeter out of step with little warning (blame that semi trailing arm rear axle), but I’m not sensing such attitude from this reborn roadster, which carries itself with familiar robustness yet exhibits a whole new level of composure. That’s a reassuring feeling when the road is yet to wring mid-spring from its surface.

Forget what you know

With fabric roof manually stowed in the boot I should be mercilessly open to the elements, but the windscreen, side windows and draught stop keep the chilling air away from my face, leaving me to carve an ideal line through each bend without distraction, and enjoy the analogue thrills of the machine pulling it off. It takes only metres to realise this is not your average R107SL, and a few metres more to suspect that it’s something rather special. One blip of the crisply responsive throttle to match revs for a lower gear, then hard acceleration and everything is confirmed under the spell of a purse-your-lips-gorgeous cacophony of six cylinders on the move: this Mercedes-Benz dares to be different and is an absolute riot.

The car in question heralds from the SL Shop is the Worcestershire Company’s answer to the question: can you turn an R107 SL into a proper sports car? Finished in Signal Red and sitting a full 80mm lower than the standard 300SL on which it is based, disbelieve quickly turns into approval. Wander round the back of the car and you’ll notice the boot’s square design looks far more butch when seated lower to the ground and just above negatively cambered rear wheels, while the stainless steel, twin-pipe exhaust perfects the stance of what could be a classic racer primed for pounding round Goodwood on a Sunday morning. Also lowered is the kerb weight, which comes in a t 1,410kg including 50kg of fuel, or two thirds of a tank.

A new dimension

Trawl through original sales brochures for the R107 and the message is clear, that it’s a safe, well-built, reliable and comfortable car. But sporty? Mercedes-Benz appears to rely solely on the car’s ‘Sport Licht’ badge to announce that disposition, suggesting it’s not really what the R107 s about. During its 18-year production cycle, from 1971 to 1989, Mercedes-Benz fitted everything from a 2.7-litre straight-six to a 5.5-litre V8, all with just enough power to motivate the surrounding metal but hardly capable of tearing rubber from modestly sized wheels.

This remastered six-cylinder is a different story, however, and not just because it’s carrying a shortened and reconfigured throttle linkage, and connected to the five-speed manual gearbox rom a 1990s C-Class. There may be a familiar three-litre M103 straight-six under the bonnet, but its crankshaft and flywheel have been lightened and balanced, its cylinder head ported and polished, the injection system modernised with larger and more advanced Mercedes-Benz injectors, and there’s a performance camshaft to enliven response in the meat of the rev range. Complete with a custom exhaust manifold, this motor wouldn’t look out of place in a fine jewellery box and now develops 255bhp, up from 185bhp. Torque, meanwhile, has increased 34 per cent from 188lb ft to around 250lb ft.

All of which means you’ll arrive at 62mph in 5.9 seconds and won’t stop accelerating until you reach 166mph, compared to 9.6 seconds/126mph for a standard 300SL with a five-speed manual transmission. The SL Shop’s Sam Bailey revealed that during testing a 500S: differential allowed the car to hit 189mph on a rolling road but acceleration took a hit. In all, The SL Shop spent two years developing its new 300SL SportLine and Mercedes Enthusiast is the first publication to get behind the wheel.

Think prototype, as this example is, and you expect roughness around the edges, but the SportLine’s cabin is brimming with carefully considered details such as nappa leather/Alcantara seat upholstery laid out in period style, and a leather dashboard, steering wheel, gear lever and surround with contrasting red stitching woven into place by hand.

Driving home the SportLine mantra is a black on white instrument cluster which glows red under darkness, and to the driver’s left is a centre console layered with pepperwood trim which extends across to the glovebox with additional ‘SportLine’ lettering facing the passenger. The only aspect that jars is the digital fuel and air gauge seated between the two air vents on the centre console. Granted, it’s reassuring to know the engine is breathing as it should, but I’d be asking The SL Shop to fit an analogue clock or ambient temperature gauge instead.

That detail aside, I think you’ll agree this car is endearingly ambitious, promisingly potent and tantalising to look at, the alloy wheels inspired by Mercedes’ ‘Mexican hat’ style of the time, but constructed to more modern measurements of 15 inches with 7J offset. Behind them sits vented and grooved brake discs grabbed by fast road pads that squeeze the life out of speed gained in dramatic fashion. 

A path less travelled

In pursuit of driving nirvana, The SL Shop took the bold step of choosing the gearbox type most R107 buyers avoided, but do not be put off because the five-speed manual here is a revelation, specialist rebuild work giving the lever a modest throw and ridding the system of its wooden feel. So much so that I find myself changing gear just for the hell of it – any excuse to hear the six-cylinder’s voice, which rasps up to 3,000rpm then really comes on song with a hard edged naaaooOOOWWW until you bleed out of the power band beyond 5,000rpm. Sam Bailey and his team spent many hours pursuing the ideal final drive ratio, the set-up of this prototype promoting full use of lower gears. If anything, though, I reckon they could close things further still, third gear firing you from sub 20mph to well beyond the national speed limit, meaning fourth and fifth are ideal for pottering in traditional SL style

And that’s the beauty of the 300SL SportLine; additional depth has been found in the R107’s abilities without sacrificing that which many find so endearing. 

The bespoke coil-over suspension developed with Bilstein means the ride is modern car taut, yet still smooth enough to brush aside a back-road blast or motorway jaunt. Meanwhile, the SL’s recirculating ball steering system should be a hindrance but it’s been breathed upon by The SL Shop and is easily the tightest I’ve ever used, relaying messages in a more detailed way.

Coupled with suspension perfected by racing engineers, the SportLine invites you to push harder and drive it in such a way that is totally at odds with its breed. Heel and toeing, and using weight transfer to tuck the nose into corners whilst braking should feel ridiculous in an R107, but those actions come practically as second nature, such is this example’s transformation. Once the bespoke Quaife limited-slip differential is installed, the Sportline will put its power down even more readily and even offer the possibility of smoky oversteer. Imagine the sight of that!

So, what’s next for The SL Shop’s new venture? Two orders are already on the books at £150,000 a pop – that figure sounding steep until you realise it covers a donor car and full nut and bolt restoration to the company’s high standards. Sam tells me he’s had several other customers expressing great interest, including in a V8 version which should develop around 340bhp. Bespoke transmission options including automatics are also in the works, promising to cover yet more niches that you never knew existed until now.

Lost in the moment 

Engrossing is not a word I use lightly, but it describes the 300SL SportLine’s drive perfectly. Fitting a manual gearbox was a bold move but the result is quite extraordinary, gifting the driver that final facet of interaction with a vehicle purpose-built to be driven with intent. As far as I can tell there only seems to be one catch besides the price, and that is the possibility of eternal disappointment in other R107s because they don’t drive like this one.