World’s fastest piece of mobile scaffolding gets a new chassis and turbocharged engine

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The Ariel Atom 4 is now a mainstay of the niche British sports car roster, and one of the most formidable driver's cars on sale today. When the 4 was launched in 2019, it promptly won back-to-back Autocar Britain's Best Driver's Car titles.  

The very first Atom, though, arrived just in time for the millennium, with 190bhp from a naturally aspirated 1.8-litre Rover engine. Launched in 2003, the Atom 2 that followed had as much as 300bhp courtesy of a new supercharged Honda unit, and that was a recipe Ariel stuck with for the Atom 3 of 2007.

Ariel makes no attempt to hide its association with Honda, which has long provided the Atom’s engine. This is the first time the car has used turbocharging, which has increased accessible torque by as much as 75%.

But the next chapter in the Atom story dispensed with the pleasantries: the winged Atom V8 of 2010 packed 500bhp from a 3.0-litre unit that started life as two Suzuki motorcycle engines. It was a bonkers, 25-off machine we described as being “brilliant to its core” despite the £150,000 asking price (barely enough to cover its costs) and it demonstrated that the employees at Crewkerne could build a genuine world-beater.

Ariel returned to relative normality with the introduction of the Ariel Atom 3.5, which in 2013 reprised the 2.0-litre Honda unit in the Atom 3, only this time with up to 315bhp to go with the slimline new headlights and an even stiffer chassis. Naturally, it was subtly but noticeably better to drive than the previous Atom, and Ariel’s waiting list duly grew - particularly as it added the Nomad and Ace motorcycle to its range. That'll be supplemented by the Hipercar too.

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But back to the latest Atom, the 320bhp Atom 4, and its even harder-performing derivative, the 400bhp Atom 4R, launched in autumn 2023. As is standard for Ariel, you should expect brilliance from both.

The Atom 4 line-up at a glance

There are two 4s: the regular car, and the faster, more focused 4R. Back in 2004, Ariel toyed with a cheaper Atom, the 160, a ‘feeder’ version of the Atom 2, with engine power pegged at 160bhp – but it didn’t last long. You shouldn't expect a reprisal of a slower budget alternative.  Customers wanted the quicker ones: a supercharged engine came as a factory option early on and a precedent for the shape of the range was later set by the 3R, with an even more track-focused set-up and more power than the regular Atom 3. That's a path followed today by the 4R, launched in autumn 2023, which raises the 4's power output from 320bhp to 400bhp.

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Ariel Atom 4 2019 road test review - hero side

When you buy an Ariel Atom, you’re buying a machine hand-assembled by a single technician. This process hasn’t changed much from the days of the first-generation car. However, the design and hardware for the Atom 4 and 4R are markedly different from that of even the immediate predecessor, the Ariel Atom 3.5.

The core principles remain: the exposed exoskeleton acts as a basis for aluminium double-wishbone suspension controlled through adjustable pushrod coilover spring-and-damper units. Bilstein dampers are standard on the base car, though adjustable units from Ohlins with remote damping reservoirs, specially made for Ariel, are an option. The 4R gets uprated versions of these, mated to either a special track or a road/track springs.

Attractive pushrod-actuated spring-and-damper units can be seen through the Atom’s steel exoskeleton. Our car uses optional Ohlins hardware, which, with yellow springs and gold casings, is particularly eye-catching

The car’s unassisted steering is a long-standing trait; likewise its mid-mounted transverse engine that drives the rear axle through a six-speed manual gearbox and a mechanical limited-slip differential. There is an optional AP Racing brake upgrade kit, standard adjustable traction control electronics, and a turbo boost controller with which to limit (or unleash) the propulsive potential of the turbocharged engine. The 4R has Ariel's first ABS option too, and better brakes still. A pneumatic-shift six-speed sequential manual gearbox is a 4R option, while it also gets improved cooling for the engine in its sidepods. Both 4 and 4R have the option of track-day appropriate wings. 

Though made from steel, the tubular chassis builds on what Ariel learned with its experimental titanium chassis of 2014. The bronze-welded tubes are therefore wider in diameter than ever, which helps make the car 15% stiffer than its predecessor. There’s also now greater leg room and better protective properties in the event of front impact, though the 4's dynamic behaviour is also said to have benefited from new suspension geometries (and these were not simply tweaks – there are fresh pick-up points, plus anti-squat and anti-dive measures), and a staggered wheel set-up, 16in diameter at the front, 17in at the rear.

The car’s turbocharged engine comes from the current Honda Civic Type R, meaning you get the rather marvellous K20C oversquare 2.0-litre four-cylinder i-VTEC engine with 316bhp and 310lb ft, so long as you’ve got the boost control in its highest mode. Optionally this can be 350bhp on the 4, or comes in at 400bhp on the 4R - though you can turn the boost down should conditions not allow. 

Ariel estimates the kerb weight at 680kg in full running order, or 700kg for the R, which still ranks it as among the very lightest on the road. Our test car weighed in at 680kg with a full tank when we tested it at a proving ground in 2019, and that was with plenty of options equipped.

The Atom's (relatively) limited top speed of under 170mph highlights the designers’ considerable battle with drag, though improvements were made for the latest generation. All the car’s panels – most of which are available in carbonfibre – are new and the old roll hoop is now neatly enclosed with the air-intake bodywork. Never before has the Atom sat so low and wide on the road.


Ariel Atom 4 2019 road test review - seats

Because it so obviously exposes its driver to their immediate surroundings, it doesn’t seem accurate to describe the Atom as being in possession of a traditional car interior.

Cockpit seems like a more apt choice of word; and as far as cockpits go, even in the world of track-bred thrill machines, the Atom’s is still a wonderfully sparsely finished one. Stripped out and with no room for anything but the functional, there is almost nothing here to distract you from the task of driving – particularly if you’re prepared to excuse Ariel’s decision to offer a fitted motorbike satellite navigation system in the car as an option.

A pair of individual plastic buckets seats (moveable only if you unbolt them first) provide decent support, and elsewhere there’s a gearlever, three pedals, and a smattering of buttons and switches housed behind a relatively small-diameter, suede-upholstered steering wheel.

The closest an Atom comes to having a bona fide infotainment suite is the GPS lap-time recorder integrated into the digital instrument display. It consists of a receiver mounted just ahead of the cockpit, which can automatically detect when you’re on a circuit (at least in the UK) and uses satellite tracking to record and display your lap times on the screen in front of you. 

One optional extra is a reversing camera, which sees through a lens housed just beneath the rear foglight, with the video feed being automatically transmitted to the digital instrument screen as soon as reverse is selected. Given how limited over-shoulder visibility is with a helmet on, it’s very welcome.

The low, thin sheet of clear Perspex that runs the width of the scuttle, with upright protrusions ahead of each seat, is more wind deflector than windscreen. Today it's standard, but if you can't bear to be that exposed, a full windscreen is available as an option (which renders a crash helmet less crucial).

Clambering over the Atom’s intricate exoskeleton spaceframe in as graceful a manner as the elasticity of your trousers allows, and then lowering yourself down into the driver’s seat, certainly brings with it plenty of sense of occasion. Once you’re in, the view immediately forwards and sideways is almost entirely unimpeded, although that sense of remarkable visibility takes a bit of a hit when you realise that driving a screenless Atom is something you’d only ever do with a helmet on.

Otherwise, the car’s general ergonomic layout is excellent. Storage space becomes a rather moot point when you realise that there is little more you’d carry in an Atom that you couldn’t fit in a rucksack or in the storage box of a superbike; and in that respect, cars like the Caterham Seven do have a practicality advantage over it. Still, there is a small compartment under the nose cover that’s big enough for a drink and an energy bar or two. Which is handy, because as you’re about to find out, you’ll probably be in need of them.


Ariel Atom 4 2019 road test review - engine

We've extensively driven both the Atom 4 and the Atom 4R on both road and track, but have only obtained full performance figures on the 4, when it underwent a full Autocar road test. 

The clear evidence was that the world’s fastest piece of mobile scaffolding didn't need to be driven with much gusto to feel like a true performance heavyweight. Stick it in fourth gear and the Atom 4 will go from 30-70mph in just 4.2sec – as quickly, but for a solitary 10th of a second, as a 715bhp Aston Martin DBS Superleggera will. Taking on long dual-carriageway-born distances, the Atom can overtake with real urgency from both low revs and high.

A lap time squarely in modern supercar territory, and only half a second slower than the Atom V8 managed in 2011 (1min 8.4sec), is a seriously impressive showing.

And, predictably enough, it gets off the line rather smartly as well. The Atom comes with optional-fit electronic launch control, although its use is equally optional. If you prefer, just dial the traction control down to zero, select second gear, wind engine revs up to the static limiter automatically imposed at 5000rpm, and then choose how much wheelspin you want by the vigorousness of your clutch action. Even when bypassing first gear altogether, you can still get wheelspin as the turbos really spool, but get the juggling act perfected and this car will hit 60mph from rest as quickly as a £300,000 exotic.

Our fastest one-way 0-60mph run was 3.1sec; the car might even be a sub-3.0sec prospect on a perfect surface and without a passenger on board. Ariel claims the 4R certainly is. It has tested it (we haven't yet verified it) from 0-60pmh in just 2.7sec, with its sequential-gearbox banging through shifts quicker than you could possibly match in the standard six-speed manual, no matter how easy and precise its shifts.

The turbocharged engine needs a second or so to inhale before it delivers big torque at middling revs, but it retains the surprisingly delicate fine throttle control and distinguishing appetite for revs that Honda’s latest four-pot turbo evidences in other applications. It sounds good at high revs, too, when there’s plenty of combustion noise and not too much of its inductive counterpart. The 4R whistles and coos in a way that the 4 doesn't.

It doesn’t have the perfect linearity of delivery, that hairline responsiveness or the banshee wail of the old supercharged engine, however. Nor, it should be said, of the supercharged Caterham 620. There are times when you miss the high-rpm theatricality and reward of the Atom’s old supercharged motor, it’s true. But you can’t deny that Ariel has to move with the times and simply adopt the best of what’s available for this car to allow a future for it.

The Atom 4’s turbo four is, in all probability, the finest engine of its kind that a company like Ariel could have appropriated for it – and, turbocharged or not, remains a very worthy fit.


Ariel Atom 4 2019 road test review - chicane front

The Atom is a brilliant-handling car, whether you opt for the standard 4 or the even more extreme 4R. Both are thrilling on road or track. This is, after all, a car that as standard finished first in our Britain's Best Driver's Car shootout in 2019 and 2020, and only just missed out in 2021 (it finished second to the Porsche 911 GT3). 

You need to keep both hands on the small, perfectly placed, Alcantara steering wheel of the Atom 4 to guide it confidently, even at everyday speeds. The rim is quite heavy – but it feeds back information from the front contact patches in a wonderfully lucid and meaningful way that’s the perfect introduction to the deliciously involving, analogue driving experience you’re diving into, fingertips first.

For me, the Atom’s so brilliant to drive because of its flaws, not in spite of them. It rolls and pitches that little bit more than the average wing-tastic, mid-engined track missile – but also communicates so much better, and has masses more dynamic charm

The car’s steering ratio doesn’t feel particularly direct, rather very intuitively paced, and is well suited to a small, light, naturally agile car. It also communicates load brilliantly as you add lock, giving you supreme confidence as the front sidewalls begin to flex; and letting you know, as that load ebbs and flows, whether the grip level underneath you is rising or falling. Come good weather and bad, then, you’ll always know where you are with this car.

Over the years Ariel has evidently calmed the propensity of the Atom’s steering to kick back over bumps and to tramline slightly, and so only at low speeds and over particularly sharp edges do you feel the need to tighten your grip on the wheel. And yet, whatever speed you’re travelling at, the sense of intimacy with the Atom’s lightly loaded front wheels remains truly striking. On track, as the tyre temperature builds, it’s almost as if you can feel the carcasses warming in the palms of your hands.

In initial track testing, the adjustable Ohlins suspension of our Atom 4 test car was set fairly permissively for compression and rebound damping – by Ariel itself, we should add – but a little experimentation proves that, even if you crank up the dials, this remains a dynamically characterful car. It likes to move around on its suspension springs a little bit, and to master it you need to learn to manipulate its mass not unlike you might that of a sports bike or even an old Porsche 911.

That’s a process you can begin on the road, as you develop a sense of the Atom’s rearward weight bias and its surprisingly rangy gait over bumps, but it becomes really absorbing and wonderfully vivid on track, and one to savour for every delicious moment.

The firmer and more focused your Atom, the less of a character trait this becomes. A 4R, even on the road/track spring set-up rather than the full track springs, is more tightly controlled, with very limited roll and, while the steering still adds weight and feedback, you have to worry less about its body movements as it goes in and out of slides. It's a wonderfully balanced track car.  

Even with those adjustable Ohlins dampers set to a more track-biased configuration, the Atom’s primary ride exudes a level of compliance that, at first, seems at odds with its hardcore ethos. It takes undulating surfaces in its stride with sophisticated suppleness, and successfully rounds off the edges from sharper, more sudden compressions without any great compromise to its otherwise excellent vertical body control.

Comfy-riding or otherwise, though, you wouldn’t call the Atom relaxing to drive even when touring and, because of its size and all-round vivaciousness, you remain very aware of any imperfection in the road surface that’s passing beneath the Atom’s open wheels, and ready to react to each. Thankfully, only at low speeds and over the worst lumps and bumps will you find that you really need to. Generally, the car tracks straight and doesn’t seem particularly highly strung by the standards of its peers.

Now much more physically draining than the car’s dynamic temperament is how exposed to the elements it leaves you. There’s no heater: your own warmth will depend solely on the weather and how well dressed you may or may not be for it. Some physical effort is required at motorway speed to keep your head steady in the wind, which quickens the onset of fatigue.

Then there’s the noise. At idle, our microphone returned a reading of 74dB, and shot to 92dB at a 70mph cruise – which is definitely earplugs-within-a-helmet sort of refinement.

The seats are comfortable at first, if a bit unforgiving over distance. Most of our testers agreed they did a good job of holding you in place, though the lack of lower back support proved a minor issue for some. In short, you probably wouldn’t want to spend more than an hour in an Atom without a break – and most owners won’t plan to. Imagine using it like a superbike and you won’t go far wrong.


Atom 4R 2023

It seems incredible that something with supercar levels of performance and utterly peerless driver engagement can be had for as little as the Atom's entry price. But it can get expensive quickly. The Atom 4R is more than £70,000 even before you put options on it and both 4 and 4R come with an extensive list of tempting looking extras.

But it pays to remember the fact that Ariels are as good as immune from depreciation, too; examples of the Atom 3 and 3.5 are listed on classified sites with asking prices in excess of £40,000 at five years old. Some highly-specced 4s can have a few thousand miles on and are still priced at six-figures. That bodes very well for the ownership credentials of even the most expensive versions.


Ariel Atom 4 2019 road test review - static

Having played the renegade on the ultra-lightweight sports car scene for so long, the Ariel Atom has now become a key part of the establishment it once sought to disrupt. Such progression doesn’t happen by chance and this car is so typical of how cleverly its maker has developed it over the years to retain what makes it so special.

In a visual sense, the Atom remains an appealing car to anyone who likes the idea of being able to see their car working, to have engineering and design placed directly in front of them to enjoy and savour. It’s also so deliciously simple that it makes modern ideas of perceived quality and more meaningful built-in quality one and the same consideration.

Track slayer is unrivalled for built-in quality and dynamic character

Regardless of which variant you pick - and 4 or 4R is genuinely a case of personal taste, use case, and budget - the Atom retains so absorbing a dynamic character that it can be enormous fun on both road and track, when so many of its close rivals simply can’t do both.

If you want one, the waiting list is several years long. But we’d bet that it’ll still be the outstanding car of its kind in three years' time, just as it so plainly is today.

Additional testing by Matt Prior

Richard Lane

Richard Lane
Title: Deputy road test editor

Richard joined Autocar in 2017, arriving from Evo magazine, and is typically found either behind a keyboard or steering wheel.

As deputy road test editor he delivers in-depth road tests, performance benchmarking and supercar lap-times, plus feature-length comparison stories between rival cars. He can also be found on Autocar's YouTube channel

Mostly interested in how cars feel on the road – the sensations and emotions they can evoke – Richard drives around 150 newly launched makes and models every year, and focuses mainly on the more driver-orientated products, as is tradition at Autocar. His job is then to put the reader firmly in the driver's seat. 

Away from work, but remaining on the subject of cars, Richard owns an eight-valve Integrale, loves watching sportscar racing, and holds a post-grad in transport engineering. 

Ariel Atom 4 First drives