The electric car has steadily evolved since the introduction of the Tesla Model S over a decade ago, but there haven’t been any major leaps. Sure, cars are getting faster while battery technology is steadily improving. But it took a consumer-oriented company like Toyota to completely reinvent the steering wheel with the steer-by-wire yoke fitted to the new Lexu RZ 450e crossover.
Tesla was actually the first to introduce a yoke on an electric car. The idea dates all the way back to the 2019 Cybertruck concept but proved quite controversial, some might even say dangerous, when fitted to production cars. It got so bad that the company had to backtrack and is now offering a normal wheel as a no-cost option and a $700 retrofit for people who got the Model S and X with a yoke and don’t like it.
Lexus did what Tesla couldn’t
The problem with Tesla’s yoke is that it looks like it came off an airplane but has to work in a car. The normal steering system of a Tesla has 2.33 turns from lock to lock, which means you potentially need to rotate the wheel about 840 degrees if you want to go from fully left to fully right. Because there’s no spoke to grab at the top, this can be unpleasant at a roundabout or downright dangerous in a crash-avoidance situation.
Not so with the Lexus yoke which can turn 150 degrees to the left and 150 degrees to the right for a total of 300 degrees or 0.83 turns, which means you never have to take your hands off the steering wheel. Or should I say steering yoke?
If you did that on a normal car, it would be impossible to drive. It would be too twitchy. In fact, I know a few cars with 2 turns lock-to-lock that are already twitchy. To get around this problem, Lexus uses variable-ratio steering on a steer-by-wire system.
These technologies already existed. The Golf GTI, for example, had variable ratios since I think 2013. And Infiniti introduced the steer-by-wire steering to the Q50 that same year. Lexus probably knows about the criticism which Infiniti received and is steer-by-wire yoke an option. The RZ 450e is going to be available in a few months, but from what we understand, the yoke won’t be ready until around 2024 or 2025.
A test prototype was available at the launch of the RZ 450e on the French Riviera, but reviews are varied. Some say you get used to it within a few minutes while others say the car changes direction from very small steering input and it doesn’t feel normal. Whatever the case, this system is going to be optional and Toyota has at least another year of development time.
Why the steer-by-wire yoke is needed and how it changes everything
When asked why it developed such a system, assistant chief engineer Yushi Higashiyama gave an interesting answer to Engineering Explained. They found that EVs have an almost instant throttle response compared to regular cars and because the braking is regenerative, it too is fast. So steering felt like the driver control that was lagging in this system, and a short steering ratio was the only solution.
To do that, the Lexus RZ disconnects the steering wheel from the wheels, at least in the mechanical sense. The yoke is connected to the Steering Torque Actuator or STA while moving the wheels is done using the Steering Control Actuator or SCA.
The yoke will still provide the driver with feedback from the road, picked up by the SCA, but this is more like an Xbox controller, and certain unpleasant vibrations are completely filtered out, which is what you want on a luxury car. Engineers can still keep feedback like traction loss or colliding with larger objects such as a curb.
So is this safe?
Toyota has a pretty decent track record when it comes to safety, obviously excluding the whole airbag fiasco. And they’re doing everything they can to ensure the Lexus RZ and other EVs which use this system will be safe. Like on an aircraft, every major component of the steering system has a redundant double.
In addition, the steer-by-wire runs on a separate electrical system and is juiced from a separate battery from the one powering the wheels. Honestly, it’s probably safer than a normal steering system.
This isn’t to say the car is perfect. Reviews have criticized the small indicator of the one-touch variety, like a BMW, so it sometimes doesn’t self-cancel. But the powertrain may be the biggest issue. It’s said to deliver 220 miles on basic 18-inch wheels or 196 miles with optional 20s. That’s surprisingly low considering you can get better mileage out of “converted” EV crossovers such as the Genesis GV70 or the BMW iX3.
The battery is the problem here, as it only has 64 kWh usable capacity, about the same as much smaller EVs like the Kia Niro. The Lexus’ sister model from Toyota, the BZ4X, recently placed 3rd on Edmunds’ Top 10 list of EVs with the worst range. Maybe they shouldn’t have tried to reinvent the wheel after all!
