BMW’s iconic Mini brand is under federal investigation because power steering on as many as 80,000 2004 and 2005 Mini Cooper models could fail. This is the latest in a rising tide of steering-related problems. We may see more steering complaints as automakers overhaul the most basic control system on a car. This is being done in a quest for the last one-tenth of a mile per gallon in fuel economy.
The probe by the National Highway Traffic Safety Administration cites 54 complaints and “a confidential number of field reports” from Mini about sudden and unexpected loss of power-steering assist. That makes the car hard to steer and could cause the driver to lose control. NHTSA lists no mishaps due to the problem, and Mini has said it knows of none.
David Champion, head of auto testing for Consumer Reports magazine, says, “We had that on a Mini with electric steering” a few years back, and it “scared the hell out of the driver.” Automakers are switching to electric motors instead of hydraulic pumps to provide power-steering assist. Electric power-steering systems (EPS) can add 0.1 of a mpg, or more, by eliminating drag on the engine caused by hydraulic pumps.
But EPS is hard to tune to make it feel similar to the age-old hydraulic systems. It can seem numb or too light to drivers. Mechanical systems often give an audible warning – harsh sounds – of imminent failure. EPS systems, “when they fail, they fail completely,” according to Jesse Toprak, vice president at auto researcher TrueCar.com. NHTSA says starting in 2006, it has “seen an increase in investigations of vehicles equipped with electric power steering.” But the agency says it is not clear if that’s because EPS is inherently troublesome or simply is more common.
According to Mr. Champion, there will be “more issues where the steering system feels vague” as carmakers eliminate normal, slightly off-center, alignment of tires and steering. That customary “toe-in” or “toe-out” of tires improves steering response, but uses slightly more energy than when tires are aligned straight. Truecar.com says it has had “an overwhelming number of steering cases this year,” with most “involving EPS.”
Hyundai recently recalled 139,500 2011 Sonata midsize sedans because the steering shaft could come apart, causing the driver to lose control. Earlier this year, NHTSA opened an investigation into “unresponsive or loose” steering on 2009 and 2010 Toyota Corollas, which is believed to be a result of how Toyota tuned the cars’ new EPS. About that same time, General Motors recalled more than 1 million 2005-2010 Chevy Cobalts and similar 2007-2010 Pontiac G5 small cars because the electric power steering could suddenly fail.
Source: USA Today
