When Alfa Romeo introduced its Intelligent Braking System (IBS), on the Giulia and Stelvio, it was the first use in production of the MKC1 brake-by-wire system. Developed by Continental, this wraps up usually separate components into one neat package that’s lighter and far more compact than the sum of its parts.
Drive-by-wire concepts were originally aimed at making everything electronic, with no mechanical connection between the driver and the car. The idea was that electric calipers would do the braking and electric steering racks would enable fancy features such as enabling the car to take major avoiding action in emergency situations without ripping the driver’s thumbs off on the steering wheel spokes.
The MKC1 system goes part of the way to full brake-by-wire but stops short of electric brake calipers. What it does do is integrate the tandem master brake cylinder (which generates the hydraulic pressure to apply the brakes), the brake booster, the ABS unit and the ESC unit, saving about 4kg.
Aside from the packaging and weight, pedal feel can be tuned by engineers using driving simulators to give a more aggressive response on track and a more relaxed response in traffic. Another advantage is that pedal travel doesn’t increase when the brakes take a beating and get hot. What the driver actually feels is a simulator built in to the MKC1 that generates the sensation normally fed back through the hydraulics, only it remains consistent however hard the brakes are working.
Full drive-by-wire wire brakes would also allow manufacturers to dispense with hydraulic brake fluid, giving them dry chassis and production lines that have no need for the messy liquid. Complete corners consisting of suspension, wheel hubs, discs and brakes could be preassembled ready to bolt on the car. A further advantage of doing away with hydraulic brake fluid is that it’s hygroscopic (it absorbs atmospheric moisture) so needs changing at intervals.
What about steer-by-wire? Although electric power assisted steering (EPAS) is common now, mainly because it’s far less energy-hungry than a hydraulic steering pump, it still maintains a mechanical connection between driver and steering; it just takes away some of the steering effort from the driver by using a motor. Full steer-by-wire would mean decoupling the driver from the steering gear altogether and that would require a change in legislation.
Although complete brake-by-wire and steer-by-wire haven’t yet made production, another form of full drive-by-wire tech has been around for a while. Electronic throttles have no mechanical connection between the accelerator pedal and the engine’s throttle. Instead, an array of sensors on the pedal box and engine pass the information the engine computer needs to adjust the throttle and the amount of fuel injected. What’s the point? Mainly to help control fuel consumption and therefore emissions.