What is the most comfortable car on sale?

The area formerly known as the Brecon Beacons was visited recently by the new Prince and Princess of Wales.

Apparently their cavalcade of luxury cars wasn’t quite as impressive as ours, though. Standards matter – and if not the royal family, you can always depend on Autocar to set them.

Well, at least, as far as transport is concerned. If this comparison exercise had been an owners’ club meeting instead, none of us assembled participants would have even approached the expected dress code requirements. Luckily, we had a job to do – and it was thanks to a reader whose name you will know.

Formula 1 racer turned motorsport magnate Jonathan Palmer consumes his weekly issue of Autocar as avidly as you do, and at a recent meeting with us he bemoaned the state of ride comfort in modern cars – that it hadn’t advanced as quickly as so many other dynamic facets.

“Why don’t we get a bunch of the most comfortable and very best-riding new cars together, along with something much older,” he suggested, “and take a considered view on the state of the art?”

How could we decline? The standard-bearers we assembled, in descending order of price, were the recently updated Rolls-Royce Phantom VIII, Bentley Flying Spur V8 Azure, Range Rover P440e Autobiography and BMW i7 xDrive60 M Sport.

Some 10 tonnes and nearly a million quid’s worth of brand-new, super-luxury metal, then (and we were still upstaged, as Dr P arrived in his no-doubt-fine-riding Agusta helicopter).

Another reader and friend of Autocar, Joe Ward, generously brought along his recently restored 1964 Rolls-Royce Silver Cloud III as a yardstick by which to measure the accomplishments of the new boys.

And, ride comfort being not only a complicated but also a subjective question, we decided not to tackle it on our own.

Providing an alternative and especially expert take was Steve Randle of Randle Engineering, a man with an impeccable CV in vehicle dynamics engineering on which the McLaren F1 can be found. Steve Cropley will be your guide to his thoughts and impressions of these cars, as well as those of Palmer, later on.

Quick links: Explaining ride comfort - Rolls-Royce Silver Cloud - Rolls-Royce Phantom - BMW i7 - Bentley Flying Spur - Range Rover - Noise levels - Results - Final verdict - Specs

How ride comfort is measured

It feels a little odd to have a whole group test in which to zero in on one particular aspect of vehicle performance. I can’t think of a more interesting field of cars in which to do it, though – nor a more revealing blend of surfaces than those that rise, twist and wriggle their way over the eastern Brecon hills.

From cattle grids and crumbling verges to sunken gullies and sharp, blind crests, every kind of lump, bump and hollow that you need to form a full picture of the isolation qualities of any chassis exists here.

Much as I love to learn about this stuff, I’m quickly bamboozled when someone like Randle starts talking about longitudinal hub compliance, roll centre height, axle droop and the like. Ride quality is devilishly hard to anatomise – but nevertheless we can all tell a comfortable-riding car from its opposite.

We tend to break the subject down into primary and secondary ride. The first broadly concerns how much a car’s body pitches, rolls, heaves and bounces relative to the ground as it travels; the second how its wheels and axles move relative to its own body.

That’s to exclude the top-level comfort of a car’s seat and its driving position, though – which, when you really concentrate on it, can have a defining influence on ride comfort all by itself.

It also skates blithely over topics like surface-noise filtering, ride suppleness, body rigidity, damper response, close body control head toss and bump-thump isolation. (I haven’t made up any of these terms, I promise.)

Softness is as good a place to start as any. At the simplest of levels, soft-riding cars are comfortable ones, or so we’re encouraged to think. So which of these cars feel genuinely soft?

Rolls-Royce Silver Cloud

Only one, funnily enough: and it’s not the old one. On its 15in wheels and 75-aspect tyres, I expected – perhaps wanted – the Silver Cloud to feel like the gentlest, waftiest car in our quintet.

But this quite clearly is a six-decades-old car on leaf springs and with a live rear axle. It rides softly, lacking only a little ride compliance and dexterity compared with the modern cars, but shows its age in every little twitter and creak of its gorgeous, graceful body and chassis.

Even so, it hovers, woofles and sweeps its way over a testing B-road so demurely, keeping its passengers comfortable, thanks in no small part to seat cushioning into which your backside disappears a little as if into a beanbag chair.

Rolls-Royce Phantom

But it’s the Silver Cloud’s descendent, the Rolls-Royce Phantom, that really wafts – and, a little surprisingly, it’s the only modern limousine here to do it.

That’s a choice on Goodwood’s part. Rolls-Royce wants its flagship to feel more luxurious than anything else, so it has allowed it a softer-sprung, longer-travel ride gait than anything else in the modern super-luxury class. As we will come to later, it’s had to accept a few compromises as a result.

The bigger picture, as Rolls-Royce will see it, is that on the averagely well-surfaced roads over which any Phantom will travel for 99% of its life, it floats along in a way that feels almost supernatural. It glides over longer-wave inputs.

At just-so speeds it swells its way almost imperceptibly over crests and through compressions, taking the sting out of every little camber and gradient change. And, over the vast majority of roads, it’s little short of wonderful.

But it isn’t a perfect-riding car – not least because, as this exercise has handily reminded us, such a thing can not exist, no matter what it may cost.

The biggest surprise of our day was how clearly the Phantom’s ride could be exposed by sharper inputs.

The impact of these incidents is made to feel all the starker for two reasons: first because the Rolls-Royce’s ride is so good on smoother Tarmac that the sudden contrast inevitably seems harsh, and second because the Phantom’s pervading noise isolation is so good. It’s a bit of a victim of its own success.

At the same time, the sheer size and weight of the Phantom’s extruded-aluminium chassis becomes a factor. Physics dictates that making a body structure so large and long rigid – and therefore immune to body vibrations – is difficult.

So just occasionally, you can feel it momentarily shuddering ever so gently when the axles are working especially hard.

Well, well – there’s a turn-up for the books. We should remember, of course, that we had to go looking for road surfaces tough enough to punish and expose the big Roller in order to learn that about it, and only could we do it after back-to-back driving in the company of some of the most comfortable rivals we could think to pitch it against.

BMW i7

For that soft-and-wafty feel, next in line is the electric BMW i7. The BMW’s sense of ultra-low, parking-speed plushness is actually better than any other car’s here.

It begins to feel a little firmer, more reactive to the road surface beneath it and more typically BMW as speeds rise. But even so, its overall ride comfort is very impressive indeed.

Bentley Flying Spur