Opposite Lock: High Definition – BMW BLOG
We live in an age where clarity rules. The clearest phone reception steers buyers. The most vivid picture is sought after by television viewers. The thinnest condoms are most popular. You get the idea. Yet somehow, we’re to believe that too much clarity and sensitivity through the steering wheel is undesired.
Conveniently, at the same time that electric steering assist came to market, auto marques started to explain how their steering “filters undesired feeling” from the steering, leaving behind only what drivers want – which is, presumably, vague steering feel or at minimum: lower definition.
Well, wheeled comrades, I’m here to tell you that I demand more. More clarity from my cell phone, more vivid images on my LED TV, and more steering feel, in all its naked glory.
We all know the burdened truth of modern steering systems – automakers have sacrificed steering feel in an effort to reduce emissions and fuel consumption. By installing an electric power steering assist, or “EPS”, carmakers are saving, on average, about 1 mpg. This does add up, and I’m not about to suggest that the benefits of EPS are diminutive or irrelevant. For the vast majority of vehicles, most drivers would likely not notice or care if they had a little less feel translated up through the wheel and for them, the economic and environmental benefits should prevail. But drivers of sports cars and sedans do care about steering feel.
And so they should. Steering feel is one of the most intimate aspects of the driving experience. The only other contact points in a car between man and machine are felt on your bottom and back, through the seat. A less bolstered, firm but supportive seat will also translate what the wheels and chassis are doing – right into your backside. These sensations aside, you’re left with vision out of the car, aural messages from the engine, tires and possibly the suspension or chassis (if things aren’t going well) and smell, perhaps the smell of an overheating clutch, smoking tires, or an electrical problem. In some way, steering feel supersedes them all when it comes to performance driving. Only chassis and tire feel through the seat is as important as steering feel on the racetrack, and there, they’re about equally as important when grasping for tenths.
There is an interesting correlation between the amount of steering feel offered up by the EPS system and the weight of the vehicle said EPS system is installed in. I at first wondered why the steering feel and clarity available in the new F20 1 series is so drastically superior to that offered up in the 3 series or woefully vague 5 series when the technology used is identical. As it turns out, less boosting is needed the lighter the car is (less friction in the front tire patch, thus less power boosting needed to fight it) and this bodes well for sports cars as the lighter they get, the more feel they tend to offer up through their EPS systems. Of course, there are other variables at play, for instance the type of EPS mechanism used and its location in the steering system (rack mounted systems tend to give the most feel), but by and large there is a heavy price to pay for vehicle weight when it comes to feel and feedback provided by EPS systems.
It’s been said that, in the M5 or Porsche 911, for instance, there is enough feel and sensation through the steering wheel to perform at the limit without any handicap. Those are my words, and echoed by others; there is no doubt that this is the greater consensus, but I was surprised to hear these words from sports car makers, including Porsche. Porsche, like BMW, have long been known for the tactility of their steering wheels, but no longer is this the most profound sensation felt from behind the wheel; perhaps this now falls to G-force. But while it’s true that you may no longer feel every pebble under the tires, there is without question enough sensation to control a slide or a tire’s slip angle with accuracy. Both the M5 and Porsche 911 are lightening quick on the track.
“But the M5 has hydraulic steering!”, you exclaim, and you’d be right – it does. So why bother mentioning it in the context of this article? Because the system is well boosted and doesn’t have that gritty feeling wiggling and vibrating up through the wheel. It’s good, just not E30 grand.
I find it ironic that people are retiring steering feel as old fashioned. “The E30 is a classic car, times have changed” they’ll retort when I speak of the glorious steering feel engineered into the 3 series of old. But how is it that technology is advancing in every other field such that clarity and sensitivity are improved, but we’re losing steering feel hand over fist?
Electric motors produce an awful lot of torque, and from 0 rpm. Hydraulic fluid, on the other hand, can be compressed and squished around. When even a pebble gets in the way of the sidewall, a hydraulic system is more likely to transfer the twitch into the steering rack, up the steering shaft, and into the steering wheel. The greater and more consistent torque of an EPS, on the other hand, is more likely to fight that twitch and mask the pebble.
Among all of the auto marques, BMW stand among the best when it comes to the quality of their EPS systems, and the subsequent steering feel they offer drivers. Porsche and MINI (yes, BMW owned) are right there beside them, with some of the best EPS on sale.
Will EPS systems continue to improve? Undoubtedly. And as consumers voice their concern and vote with their wallets, automakers will listen. The next generation of EPS assist will no doubt add more feel and higher definition. I eagerly look forward to my first drive in the all-new M3 – a car which will likely possess an EPS (though not for certain; consider that the M5 uses hydraulic steering assist while the regular 5 series (except for xDrive models due to packaging reasons) features EPS). I also look forward to sampling Porsche’s new GT3 upon its release and comparing how the steering feels verses the 911 Carrera S.
In the mean time, I’ll giggle and grin behind the wheel of any MINI, or F20 1 series, as they deliver high levels of clarity through the wheel despite their EPS systems. These cars are seriously fun to drive, because they talk to you and converse through every corner – they prove that EPS need not be a dirty acronym.
Bring on Electric Power Steering 2.0.
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