At its peak in the back of the Atom 3.5R, Ariel’s old K20Z four-cylinder supercharged Honda engine produced 243lb ft of torque just above 6000rpm; the new K20 turbo makes 310lb ft at half that crank speed – in a car weighing so little as to make such a gain in accessible torque feel very significant indeed.
The upshot is that the world’s fastest piece of mobile scaffolding no longer needs to be driven with much gusto to feel like a performance heavyweight. Leave 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.
And, predictably enough, it gets off the line rather smartly as well. The Atom now 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 £40k car will hit 60mph from rest as quickly as a £200k exotic.
Our fastest one-way run was 3.1sec; the car might even be a sub-3.0sec prospect on a perfect surface and without a passenger on board. 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.
It doesn’t have the perfect linearity of delivery, that hairline responsiveness or the banshee wail of the engine it replaces, however. 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.