The two primary types of power steering, hydraulic-powered and electric-powered, have been in common use for passenger vehicles for decades now. However, virtually all new cars on the market now use electric power steering due to cost, reliability, and user preference. Despite this, many enthusiasts profess to still favor hydraulic systems. Here, we’ll examine how the two different systems work, what the differences are, and if one really is better than the other.
What is Hydraulic Steering?
First commercially pioneered by Chrysler in 1951, hydraulically-powered steering (or HPS) uses an engine-driven hydraulic pump to amplify the load being applied to the steering rack, reducing the amount of effort needed to turn the wheel. The idea behind the system was to increase ease of maneuvering, especially at parking lot speeds, giving the driver more comfort and control while driving.
General Motors’ Cadillac would launch their own power steering system the next year, and the option soon become fairly widely available in publically-available vehicles. However, it would remain a pay-extra option on many vehicles well into the 1980s. As an example, it was an option on the 1984 Ford Mustang (though standard on the GT trim).
Before hydraulic steering, steering systems were “manual,” sometimes referred to today as non-power steering. Even many hardcore enthusiasts will relent that, although this provides the most "natural-feeling" system, the drawbacks are not worth it. If you’ve ever steered a car that had a dead battery or was not turned on, you know how much physical effort it takes to operate without power steering, especially at low speeds. And those that drive antique vehicles with unassisted manual steering know that parallel parking in one of these older cars can be a real pain. Virtually no modern cars do not have some sort of power steering, though the Alfa Romeo 4C stands out as a notable exception.
While hydraulic power steering offered greater comfort and control to consumers, it was slowly outmoded by electric power steering. Today, few cars with hydraulic steering are still available on the mass market, and most that do are light trucks, such as the Toyota Tacoma. One the performance car side of things, one of the only options remaining is the Subaru WRX Sti.
What is Electric Steering?
Electric steering, also known as electric power steering, EPS, or electrically-assisted power steering, is a set-up that uses an electrically-boosted motor to control and reduce steering effort needed in a vehicle. It is the latest in standard steering technology and used in virtually all production models that are currently sold.
With electric power steering the new norm, it's up to manufacturers to offer programming that gives enthusiasts the steering feedback they want.
Electric power steering is also sometimes referred to as “electronic power steering,” but this is generally regarded as incorrect; the “electric” aspect of electric power steering actually refers to the electric motor itself. With that said, this technology allows the car's computer to give customized steering feel that can even be changed on the fly. Moreover, EPS is necessary to allow for semi-autonomous and autonomous driving systems, such as lane-keep assist.
As we’ll see below, some enthusiasts are nostalgic for the hydraulic steering systems of years gone by. Though it’s not a problem intrinsic to electric power steering, many modern systems offer a vague on-center feeling, over-boosted lightness, and overall less feedback from the road in terms of what the car’s tires are actually doing.
Hydraulic Steering vs Electric Steering
There are several primary reasons why electric steering has become the default system over hydraulic steering. A non-negligible benefit EPS is the increase in overall fuel economy, as the system does not require power from the engine. Moreover, electric power steering systems require less maintenance; You won’t have to fill any additional fluids or ever worry about leaks. Plus, the hydraulic steering pump must constantly be running, even if the wheel is not being turned, which leads to more drain from the engine and lower overall efficiency. All of that, combined with the fact that electric steering is cheaper to manufacture, means that it is the de-facto go-to for almost all modern vehicles.
Performance-oriented cars like the Focus ST provide sporty steering, but some say that it still doesn't match the feedback of a hydraulic system.
Electric steering also gives drivers the option to choose different drive modes with drastically different steering feel. Examples include the Mustang’s “Comfort,” “Normal,” and “Sport” modes. While this could hypothetically be implemented in a hydraulic steering system, the added cost and complexity of variably changing the hydraulic pressure would be much more difficult to efficiently utilize.
In terms of engineering and mechanical aspects, there are virtually no disadvantages to an EPS system. While many enthusiasts will complain about the lack of feedback and the numb feeling of an EPS vs HPS system, in reality, this experience is a product of the design of the system. An electric power steering system could be programmed to behave just like a hydraulic one, or even better! The issue is that the average modern driver desires isolation from road imperfections and a light steering effort, versus the more tactile road feel and heavier steering of the past. Remember though, that lighter steering does not inherently mean less feedback; the two are mutually exclusive.
Additionally, there are a number of electric steering applications out there that are quite good, even if they don’t quite compare to the best hydraulic systems of yore. Porsche is well-regarded in this arena, and most drivers are also quite fond of the way the Focus ST and Fiesta ST handle. This goes to show that good software programming can help bring about EPS systems that offer more feedback, with a sportier, more traditional feel. But it will be up to manufacturers to provide that to drivers; that’s not looking very likely in a market where the vast majority of drivers simply don’t care that much.
At the end of the day, while track-focused drivers might want the more authentic steering feedback that the typical hydraulic system provides, the wants and needs of the mass market dictate that electric steering systems are the new default. With smooth, sharp steering, hardcore enthusiasts are really only missing out on that tactile road feedback, which a good electric system could hypothetically provide. It’s up to a manufacturer to decide to do so, which is possible with advanced drive mode technology.
When Did The Ford Mustang Start Using Electric Steering?
The switch to electric-powered steering allowed the Mustang to customize the input and feedback with different modes.
While most enthusiasts focus heavily on the engine changes that occurred at the time, the 2011 model year Mustang was also the first one to use electric power-assisted steering. Although the launch of the new 5.0 liter Coyote motor in the Mustang GT was a massive change that garnered tons of attention from drivers, it’s easy to forget that the switch away from hydraulic steering was also a major leap forward. It’s just one of the major differences between the 2011 and 2010 model, and was another reason to consider one over the other. The Mustang has used EPS ever since, and while the technology will always have its critics, there are few that argue that the Mustang specifically really suffered in the handling or steering feedback department when looking at things holistically. Sure, the earlier S197 models with hydraulic steering do offer more feedback and road feel. But especially given the fact that the massive steering wheel in the Mustang is practically the size of a dinner platter, the overall steering feel could be ponderous, with slow-feeling turn-in.
The new electric steering that started in 2011 could feel more artificial than before, there’s no doubt about it. But the overall lighter nature meant that the car felt more “point-and-go”, being more nimble. Whether that feeling of quick steering in the electric system or the more “natural” aspects of the older hydraulic steering lead to the car feeling more “accurate” is up to the driver, and will certainly vary among the enthusiast crowd. Maybe the new system just takes some getting used to, but most reviewers were quite positive about how the EPS improved handling, even if it meant sacrificing the level of communication that the hydraulic system offered.
Fly-by-Wire Steering: The Next Iteration for the Market?
While almost all car models sold today now use electrically-assisted steering, there is one company that has taken things another step further in that direction. The Infiniti Q50 started using an optional technology that the company calls “Direct Adaptive Steering” (or DAS), beginning in the 2014 model year. Similar to the controls used by many modern airplanes (in a fly-by-wire configuration), the “steer-by-wire” system developed by Infiniti has no mechanical connection between the steering wheel and the car’s wheels during regular driving. In the event of a system failure, there is a mechanical backup that can help the driver safely steer to avoid an emergency.
While the technology behind the system is undoubtedly impressive, much of the initial reception was tepid at best and highly-critical at worst. A second iteration, which many thought was at least greatly improved, was released in 2016. This is still a divisive topic for enthusiasts, but now, hardcore fans of the system are quite vocal about how amazing this new technology is. On the other side of the coin, detractors argue that you can’t get a “feel” for the road, which matters less in daily cruising and a whole heck of a lot in spirited driving applications. The lack of feedback has been criticized for leading to less enjoyment and, worse, an inability to safely find the limits of the car.
The complete isolation gives drivers a vibration-free steering experience and uses advanced technology that can be adjusted up to 1,000 times per second. It's too early to say whether this new type of drive-by-wire steering system will replace traditional electric power steering in the coming years, but it is clear that the technology is only getting better.
Sources: Ford | AutoTrader | Car and Driver | Car Throttle | Popular Mechanics | Infiniti
Image Credit: Ford | Jeep