The car’s departure point is a Fiesta chassis braced in key areas on the underside of the body-in-white, which is 14% more rigid than that of the standard car. The new ST model also has the fastest steering rack and the stiffest torsion beam yet to be fitted to a performance Ford. It has particularly interesting suspension, too, that is well worth geeking out about for a minute before we move on.
Frequency selective dampers from Tenneco feature front and rear, which are double-valved to better handle both high and low-frequency inputs than a conventional passive damper could; they’re not ‘adaptive’ per se; just clever.
Moreover, Ford fits asymmetrical, directionally wound springs onto the car’s rear axle, which are effectively bent into their fittings to apply a stabilising lateral force onto the rear wheels, as well as performing the usual load-bearing job. The springs address a key problem that hot hatchbacks with twist-beam rear suspension have always had; that, in order to effectively locate the rear axle and deliver top-level handling precision, you have to fit very rigid suspension mounting bushes that have a detrimental effect on ride sophistication.
These ‘torque vectoring’ springs, claims Ford, do as good a job as a Watt’s linkage in solving that problem, permitting the fitment of much softer ride bushes – and they’re also significantly lighter than a Watt’s linkage would be.
Up front, the Fiesta ST has a dedicated front hub design of the sort that's becoming common among cars of its ilk, allowing Ford to lower the car’s ride height without lowering its front suspension roll centre too much and to keep control of front kingpin angle and wheel offset as necessary to avoid too much torque and bump steer.
The car’s overall spring rate is slightly higher than that of the outgoing car but, as the engineers behind chassis development will tell you, the new damping and bushing in combination contribute to a more mature, rounded feel to the ride – without taking that all-important playful handling balance and cutting-edge response from the handling. Sounds good. But too good to be true? We'll get to that.
Those engineers will also tell you that, while they loved the last Fiesta ST, it certainly had a yobby, antisocial ride that they simply couldn’t justify transferring directly onto the new version. However, before you doubt them, be aware that they’re the same engineers who sent the Pilot Sport 4S tyres they’d originally intended for the car back to Michelin halfway through the development programme and insisted that only grippier Pilot Super Sports would do.
The Fiesta ST’s new engine is one about which, I dare say, you might already have read: an all-aluminium, three-cylinder, 1.5-litre turbocharged motor that gives the car identical peak power and torque figures as the outgoing model’s 1.6-litre four-pot – but which can also deactivate its middle cylinder and run on 66% of its normal swept volume in conditions of light load. That’s a three-cylinder engine capable of running on two – a car industry first.
Upshot? A 20% improvement on lab-test fuel economy and CO2 emissions compared with the old ST – while, as might be of more interest, the new motor is lighter than the one it replaces, too.
This is also the first Fiesta ST to have selectable driving modes: Normal, Sport and Track. As you cycle through them, that engine gets fruitier sounding as its active exhaust and engine sound synthesising system combine to bring additional layers of noise. There’s a distant flavour of the original five-cylinder Focus ST with the way this engine warbles and the torquey mid-range feel its performance has.
I’m not totally sold on the time it takes the crankshaft to slow down from high revs, I have to say – a function of the counterbalance measures that three-pots need to run smoothly at low engine speeds. I can’t help but wonder, either, how much faster the engine would spin, and how much more power it would develop, if Ford dropped the flywheel completely. Still, perhaps that’s just me. All in all, there’s certainly plenty of urgency, plenty of character and, in spite of the torque, a likeable willingness to rev.
Elsewhere, the Fiesta ST feels like the car it replaces in lots of ways; it has meaty, fixed-ratio steering with which it’s easy to gel in spite of its pace, as well as supreme handling response and brilliantly flat body control.
But the way it rides is something else. Having only driven the car on a test track, I can’t tell you with any certainty how it might deal with a British B-road – but there is quite a lot more suppleness and ride dexterity here than there used to be. Over what lumps and bumps I could find on our test drive, over which the last Fiesta ST’s dampers might have bristled and its body fidgeted, the new model’s suspension just sucks up the punishment and lets you get on with it.
Perhaps more importantly still, on surfaces over which you might have felt the need to apologise to your passenger for the selfishness of your buying decision in the last car, I suspect you won’t have to do the same in the new one. And that’s a bit of a revelation: a Fiesta ST that passes the ‘girlfriend/mother-in-law low-speed ride acid test’. Hurrah.
Equally brilliant is the car’s handling – although that much we expect of a Ford performance product. The Fiesta ST feels a shade more precise in its steering response than the last one did, turning in more crisply, gripping harder and staying slightly truer to your intended path than its forebear as the lateral load builds into the rear tyres. It’s certainly capable of carrying more cornering speed than the last car and has a little bit more mid-corner stability, while traction on corner exit is quite subtly but notably stronger than it was through the machinations of that Quaife limited-slip differential.
But fear not: the car is still a barrel load of fun when you disengage the stability control and unload the rear axle. On a trailing throttle, the Fiesta ST can be teased into easily tamed oversteer more dependably and willingly than any other hot supermini I can think of.
Its handling balance and adjustability remain truly exceptional – in a way that speaks volumes about the philosophy of chassis engineers who think a front-wheel-drive performance car that isn’t sensitive to controllable lift-off oversteer just isn’t worth their time. And who also can’t understand why so many of their rivals seem to be so afraid of the phenomenon that they try to engineer it out of the handling mix entirely. Lucky for Ford, I guess, that they are.