Compared to the ordeal it endured with Honda, McLaren's former relationship with Mercedes looks like one of long held happiness. The British Formula 1 team and German engine supplier might have only secured three constructors titles during their 19-year partnership, but it was a period of consistent competitiveness that vastly contrasted the midfield performances of McLaren's successive alternatives. It's somewhat surprising, then, that the pairing didn't produce more road cars beyond the SLR, in actual fact, though, their sole road-going project did involve its own fair share of conflict and disagreements.
McLaren was, as it is now, obsessed with the efficiency of its machinery, with its technical boss in at the time, Gordon Murray, being the biggest advocate for keeping things lightweight and naturally aspirated. The SLR was for Murray an opportunity to produce an ultra-slim supercar with a midship atmospheric engine in the spirit of the F1; Mercedes, on the other hand, wanted to produce something more forgiving, comfortable and regularly usable. The car that was born out of the project would leave Murray dissatisfied and, almost two decades later, see him announce his own, true successor to the lightweight naturally-aspirated supercar.
Back in 1999, however, we were given the Vision SLR concept, which set the agenda according to Mercedes's demands. Five years later, the production model followed, weighing in at 1.7 tonnes and using AMG's 5.5-litre V8 with supercharging up front, driving the rear wheels through a five-speed automatic gearbox. The design was handled by AMG with McLaren's input focussing largely on aerodynamics and optimising the form; inside there were part-leather sports seats and familiar Mercedes switchgear leaving the SLR feeling familiar and easy to use, although some didn't think it exotic enough for this very reason.
Many argued the car wasn't sporting enough, either, because while a 626hp output ensured rapid progress, the SLR felt less naturally athletic than similarly exotic alternatives such as the Porsche Carrera GT and Ferrari Enzo. But the McLaren Mercedes was priced at just over £300k back in 2004, which meant it did undercut the highest realms of exotica. And it seems that many people were convinced of its talents, because sales were strong from the off, encouraging the production of several special edition variants that were priced considerably higher.
Much of the SLR's flexibility came from the strength of its base, a carbon fibre tub, which you could say was a technical precursor to the shared architecture of McLaren's present-day line-up. While the production of a carbon part was still exceptionally expensive even at a time when the material had become commonplace in motorsport and supercars, the lack of a roof section in the structure's design meant its rigidity would be unaffected by drastic body alterations that left the base intact. Its inherent stiffness also enabled the use of softer passive damping rates to give all versions of the SLR some of the most forgiving rides in the class. Mercedes's intention to produce a range of ultra-fast but comfortable supercars was achieved.
Still, enthusiasts complained about its faults. The SLR was given a torque convertor auto back in the days when dual clutches were the in thing, its carbon brakes lacked feel unless stood on and the steering rack felt too quick for the application - not to mention the hefty kerbweight that was at odds with its motorsport-esque tub. Yet, despite these supposed flaws, the SLR was an extremely loveable machine. Its M155 engine, a dry-sumped evolution of the supercharged M113 5.5-litre, was butch, burly and tough, as well as being considerably less attention-seeking than the powerplants of rivals, going 10,000 miles between services. That's in a proper supercar with a carbon tub that can crack 200mph.
McLaren's engineering know-how was most evident in the way the SLR was both savagely fast and completely on your side. With none of the spiky supercar stuff you would get in rivals, the SLR was a thunderously vocal (thanks to side exit pipes) pussycat. You could go for miles and miles without feeling tired and then, presented with a twisting road, charge along as if you'd just hopped in and revel in the performance it so willingly offered. It took some time, but slowly more and more came around to the SLR and the shift in opinions was only helped as McLaren produced even more focussed versions, which ditched some GT features for motorsport-infused raciness.
Today, the SLR's reputation is as good as ever, helped somewhat by its old school simplicity (in the context of today's supercars) but also the fact that it remains a genuinely usable high-performance offering. That being said, even a car with an extended service schedule like this will often be subjected to infrequent use, like today's Showpiece, a 3,000-mile 2008 car that's lived most of its life garaged in Jersey. It looks as fresh as the day it left Woking and at £340,000, it's priced as such as well. For someone wanting to relive an era when McLaren regularly did battle with Ferrari on the track, there are few better places to start than its Mercedes supercar.