A new upgrade package is available for the already stellar Ford Focus RS, wrapping up some of our favourite options and adding a new Quaife limited slip differential to the front axle.
The Recaro shell seats, forged 19in wheels, Luxury Pack and Nitrous Blue colour-coded Brembo calipers are all options available on the existing RS - and desirable ones at that. To set the RS Edition car apart, Ford has added matt black mirrors and roof and rear wing, with the latter also getting prominent RS badges on its sides.
But it's the mechanical upgrade to the all-wheel-drive powertrain that's of most interest. By adding a Quaife Automatic Torque Biasing differential to the front axle, Ford is offering RS owners who want to make the most of the 345hp delivered by the 2.3-litre turbocharged engine even more scope for doing so.
Put simply, where the standard RS uses its torque vectoring rear axle to push the car through its natural tendency to understeer, the new differential puts greater emphasis on the front axle. Previous front-driven RS models have used Quaife differentials to the same ends; its addition to the current all-wheel-drive model follows a similar move by Mercedes-AMG, which added a front diff option with the Dynamic Plus package on the revised 376bhp A45.
It also gives the RS an additional technical edge over the recently updated but mechanically less sophisticated Golf R, the Volkswagen relying on a regular Haldex-style all-wheel-drive system with brake-activated torque vectoring in place of mechanical locking differentials.
Our test drive in the Focus RS Edition was confined to Michelin's wet handling track on its vast Ladoux proving ground. Given the emphasis was on exploring the influence of the differential and the car is otherwise mechanically identical, this wasn't an issue and being able to do so back to back with a standard RS was a revealing demonstration of the changes it brings.
On the slippery surface of the sprinkler-soaked test loop, the standard car would respond to mid-corner throttle inputs with power understeer until the all-wheel-drive system could exert its influence. In Track mode and with the ESC in its mid-setting, it would then rotate into the RS's trademark four-wheel drifts, the transition as exciting and unruly as we've come to enjoy.
In the diff-equipped car, the sensation of it pulling from the front as much as pushing from the rear was noticeable, making the RS feeling more four-wheel drive in balance. With the diff preventing the front inside wheel from spinning up, there was less ESC intervention, reduced power understeer and a smoother, faster rotation into the corner as the torque vectoring rear axle came into play. Faster and neater, for sure. But does that come at the cost of some of that raw character the RS has come to embody?
Whether you feel the benefit of the new differential very much depends on the conditions, your driving style and intended usage. If you are a confident driver and happy steering a car on the throttle, you'll appreciate the increased composure and traction. Likewise, if you're keen to use your RS on track days and wring every last horsepower out of it, the Option Pack car has better balance into the corner and more traction out of it. For those looking to upgrade their car with the officially sanctioned 370bhp Mountune kit, it's probably a sound investment too.
Although less composed, the standard car is, however, possibly more entertaining and willing to show the hooligan side you'd expect of an RS-badged Ford. Because unless you're absolutely on it, the diff will be pulling the car straight before the rear axle can come into play. Tellingly, Ford Performance engineering boss Jamal Hameedi says he's happy sticking with his standard RS as his daily driver, appreciating the expanded reach of the diff-equipped version but accepting its benefits are really confined to the upper reaches of the performance envelope.
For those who want the most out of their fast Focus - and the kudos of having the extra tech - it'll likely be a no-brainer, though. Like an RS but a bit more so, the RS Edition sharpens its edge just that little bit further.
Read more on Autocar.