Car makers normally wait to introduce major innovations until they have a shiny new car to put them into. This makes lots of sense given the short attention spans of most motoring journalists, some of whom have been known to start snoozing during the ten-minute technical briefings that are typically given before keys are handed over at glitzy launches.
But this rigid cart-follows-horse logic isn't always the case, and certainly wasn't with the now widely revered M156 engine. This being the 6.2-litre naturally aspirated V8 that AMG had been allowed to develop by itself, its first bespoke powerplant since being fully absorbed into the wider Mercedes empire. The motor was a technical masterpiece, but development work had finished well before any of the production cars that would use it were set to be launched. And AMG didn't want to wait for the sound of applause.
So in 2005 the division organised a special demonstration by fitting the new V8 into a pair of former CLK DTM cars, painting both bright orange to stand out better in the pictures, and then booking a day at the Paul Ricard circuit in France so that journalists could come and have a go. I was one of the lucky attendees.
Nobody fell asleep in that classroom session, even though it was a fair bit longer than usual. Wolf Zimmermann, AMG's charismatic head of powertrain, introduced us to the new motor in the loving detail of a new father describing his firstborn. We learned about the exact composition of the 42CRMo4V alloy used for the crankshaft, the F1-inspired bedplate structure, the mechanical detail of the full variable timing across all four camshafts and the motorsport derived bucket tappets to ensure it could rev freely to a 7,200rpm redline. We even learned about the twin wire arc spraying technology which would give the cylinder walls - and I'm quoting from my original notes here - a "tribologically optimal surface and improved durability." (Zimmermann now develops Ferrari F1 engines, so he definitely knows his onions on this stuff.)
The hands-on practical demonstration that followed was more compelling; the cars weighing around 1,300kg and the near-production V8s producing a claimed 510hp - and doing so with little evidence of exhaust silencing. The session soon turned into a festival of over-exuberant oversteer, much of it involving the outer reaches of Paul Ricard's tarmac run-off areas. Another up-and-coming AMG engineer was on hand to demonstrate the 6.2's potency and hooligan potential - Aston boss Tobias Moers. I remember him acceding to a photographer's demand for tyre smoke with what must have been a 100ft rolling burnout.
I left the event in possession of an AMG-branded suitcase which is still going strong, but - bribe aside - also convinced that this was going to be one of the early 21st century's great road car engines. 20:20 hindsight has caused me to roll back on many of my journalistic predictions over the years, but I've never changed my opinion on that one. There was just one jarring note, when Mercedes told us the first car to get the new engine would be the hulking great second-generation ML SUV. Which didn't feel like a very obvious fit.
To cut to the chase, it took less than a year to confirm it wasn't.
The W164 was massively better than its predecessor. The first-gen ML had been offered with AMG's 5.5-litre version of the regular Mercedes V8, and had struggled to cope with the 342hp that produced - its ladder-framed chassis having all the sophistication and refinement of a matelot's 3am chat-up line. The new ML63 had a monocoque structure and shared much of its underbody with the W211 E-Class, and it certainly never felt overpowered despite having an extra 160hp. But the new powerplant never felt like an obvious choice for something so big and heavy, peak torque arriving at a very un-SUV 5,200rpm.
The AMG could be made to lift up its skirts and fly, a stamped throttle launch would blast it through 0-62mph in just six seconds. But it needed to rev to perform, and the seven-speed auto got plenty of exercise whenever acceleration was required. Until the launch of the first-generation Cayenne Turbo S, it was the fastest SUV in the world.
The need to apply welly led to the other obvious downside: fuel economy that made the ML63 into a rolling environmental hatecrime. Even in those less enwokened times the AMG's ability to gargle its 95-litre tank was close to terrifying. The official combined economy figure was 17.1mpg, and parsimonious restraint when cruising would indeed get close to that figure, or even beyond it. But urban trundling, or the sort of enthusiastic use any M156 encourages, could push consumption into the low teens, or even single digits.
Yet for those who could stomach the running costs, there was still plenty to like about the brawniest W164. Permanent all-wheel drive denied it the tail-happy handling of its rear-driven sisters, but also makes for impressive dynamic stability in slippery conditions - not to mention a respectable degree of off-road ability. Like its lesser sisters the cabin was spacious, well-equipped and much better finished than the first-gen ML and its burger box cabin plastics.
Fast forward to 2022 and although the ML63 might not be the most compelling wrapper for this sonorous engine, it does seem to be the most affordable. The M156's ubiquity at the top of the range means there is no shortage of 63-branded Mercs to choose between: C63, E63, S63, R63, GL63, CL63, CLS63, SL63 - plus the gullwinged SLS. But barring the unloved oddball which was the R63 AMG, the ML seems to be consistently cheapest when age and mileage are factored in.
We have seen and Pill'd cheaper M156-powered cars than this £15,990 Pill - the similarly aged, mildly modified W204 C63 AMG that featured last year is an example. But when both cars were new the ML63 would have been more than 50 percent dearer.
Befitting the need for some spice, our Pill has covered a reasonably serious 143,000 miles, although that figure is offset by the promise of a comprehensive service history to back the selling dealer's claims of motorway mileage. (The advert also says the most recent service happened on Thursday this week, which is enticingly precise.) As a black car that's been photographed on a sunny day there are some shiny bits visible on the front bumper which may be scuffs, but - to judge from other angles - are probably just shiny reflections. The MOT history is a restful shade of green, with nothing but inoffensive advisories in recent years. Even the last fail wasn't for any mechanical issue, flunking in 2013 when every single tyre was below minimum tread requirements. With so much performance, and so much weight, its not hard to understand the appetite for rubber.
It might seem hard to make much of a rational case for such a festival of excess, but here goes. Fuel cost peaks often seem to hit the values of the greediest guzzlers disproportionally hard, leaving them to rebound when pump prices ease. Okay, there's an obvious 'if' proviso in there too, but the very fact this car is so obviously unsuited to the world where £2/ litre seems a real possibility might make it the perfect time to open negotiations about buying it.
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