New tech reduces lock-to-lock rotation to 170deg, so there’s no need to shuffle the ‘wheel’
Mercedes is the latest manufacturer set to bring steer-by-wire to showrooms, introducing the tech on the updated EQS limousine later this year.
Following Tesla and Toyota in removing the mechanical linkage between the steering wheel and road wheels, Mercedes says the new development “elevates the driving experience to a new level and fundamentally transforms the interaction between human and vehicle”.
The company cites numerous benefits of steer-by-wire – which Autocar has sampled in a prototype car (see below) – including, most importantly, the dramatic improvement in low-speed manoeuvrability it brings.
With the lock-to-lock window reduced from several turns of the steering wheel to just 170deg, there is no need for drivers to adjust their grip on the wheel or shuffle it through their hands, which means the conventional round wheel can be replaced by this unusual yoke-style device, upon which the driver can maintain a constant grip.
Mercedes says this new arrangement gives a clearer view of the road ahead and makes it easier for the driver to get in and out of the car – which in turn “reinforces the brand’s signature ‘Welcome Home’ feeling from the very first moment”.
By removing the mechanical link between the road and the steering wheel, Mercedes says it has also been able to “eliminate” any vibrations and jolts that come through the column, boosting refinement, while tuning the system to preserve an “intuitive steering feel”.
The system will make its debut as an option on the EQS and is soon to be rolled out to the electric GLC, but Autocar understands Mercedes’ combustion cars could gain the tech as well: engineers tout the packaging benefits that come from removing the bulky mechanical steering system – potentially freeing up space for larger motors.
It also makes it much easier and cheaper to build left- and right-hand-drive cars in sequence, as far less adaptation work is required to move the steering wheel from one side of the car to the other.
The company also emphasises the high degree of redundancy that has been engineered into the system, with two separate signal paths between the steering wheel and road ensuring constant power supply even in the event of a failure. In the “unlikely” event that both fail, Mercedes says, the car can still be directed to a safe stop using a combination of the rear-steering and individually braking the front wheels with the ESP.
What’s it like to drive?
The EQS is the biggest car we’ve yet tried with steer-by-wire and could also be the one that benefits most obviously from the technology.
This is a large vehicle. At 5.2m long and 1.9m wide, its footprint is not far off a Bentley Bentayga’s and it feels every inch as unwieldy when navigating tight car parks or congested urban streets with the regular, mechanical steering set-up. Threading it through small gaps and around sharp bends requires an exhausting amount of wheel-wrenching – faintly reminiscent of piloting a trawler through a busy harbour.
But the new steer-by-wire technology, in combination with a rear axle that can steer up to 10deg, makes it feel almost as manoeuvrable as a supermini.
It takes some getting used to. Condensing the lock-to-lock rotation from several turns to just 170deg means that low-speed responses are inherently much quicker and the steering feels a lot twitchier as a result. But on my test drive, heeding the engineers’ advice to “drive more lazily”, I soon settled into a natural rhythm that allowed me to better exploit the vastly improved agility.
We took it through a low-speed slalom course and around a section of bum-clenchingly narrow turns, and manoeuvres that had been near impossible in the standard car needed no more than a relaxed flick of the wrists – and we were able to tackle them faster because of the reduced time it takes to get the wheels pointing the way you want.
The yoke never quite felt natural to hold. You can go for the obvious ‘nine-and-three’ and place a hand on each side or grip the horizontal arms like motorbike handlebars – but neither is immediately intuitive and I think I’d need a fair bit of time at the… ahem, wheel before arriving at a default position.
Mercedes has yet to detail pricing for the steer-by-wire tech and it’s likely to remain the preserve of its most exclusive models for some time but this technology is shaping up as a promising means of boosting the refinement credentials and drivability of its big cars – and it could have significant implications for its smaller models too.
