ROYAL FORD Globe Staff 10/12/2002
AUTOMOBILIA
ROLLOVER DANGERS FIRMLY UNDER CONTROL IN XC90

CONCORD, N.H. — Sometimes you need the highly technical verbiage of a trained engineer to explain the saving grace of an SUV that a slalom could have put on the edge of rolling over: "You go through the slalom and you go too fast, and the hand of God just comes down and goes, `DOINK!' " Situation under control. OK, sometimes you don't.

That was Keith Lindem talking. He's from Auburn, Mass., and has been an instructor for Stevens Advanced Driver training for 15 years.

He was talking after we'd been out on an abandoned spur of airport runway here testing to see if we could flip the new Volvo SUV, the XC90. Of course, there's no car you can't roll if that is your only mission. What we were testing, in a real-life format, were the situations that drivers of SUVs too commonly encounter because they drive them too fast.

We put the XC90 through a tight slalom course that in the past, even moving as "slowly" as 40 miles per hour, has lifted a rear wheel or put other SUVs over on two wheels in tilts that only trained drivers could fix. The everyday motorist would have rolled in these situations. The XC90 would not even go up onto two wheels, and the everyday motorist could have been doing what we were doing.

We put the XC90 through an emergency lane change (picture traveling at 60-plus miles per hour and suddenly spotting a dead tanker truck 55 feet ahead of you). Slam the ABS brakes, steer around the obstacle, and move back in front of it after passing it. Not easy for an SUV to handle. The XC90 did it with ease.

Flat out, this is a car that will save lives.

Dan Sheppard, a sports car racer out of Pepperel, Mass., took a turn behind the wheel and screamed through the slalom course, finding that the Volvo's Roll Stability Control program would not let him make a mistake, setting the car back to flat every time the body tried to roll.

"You can't induce any more body roll," he said. "The more you try, the more it fights you."

Volvo comes to the SUV market for 2003 with a distinct advantage over certain other manufacturers: the XC90 is its first, Volvo has never been associated with the dreaded word "rollover," and therefore can talk about preventing roll overs without fear of admitting past engineering flaws.

Volvo goes at protecting SUV occupants in three ways.

First, even as it provides the high seating that SUV owners demand, it keeps the XC90's center of gravity low, just 3.5 inches higher than a Volvo sedan. A main reason SUVs tip over is because their centers of gravity are too high for the demands speeding drivers place on them. It's simple physics: a brick stood on edge is tippier than a brick laid flat.

Second — and this, to my mind, is the supreme engineering feat of the XC90 — Volvo's RSC system simply will not let you make a stupid mistake. Its gyroscopic sensor system is capable of making up for the idiots who drive SUVs too fast and who, when trouble arises, kill themselves and others.

The system uses gyroscopes to monitor rate of roll and roll angle (roll is the car's rotation along its longitudinal centerline — think pig on a spit) and stops roll when it senses it is occurring too rapidly or has reached too great an angle. To do this, the system applies brakes to individual wheels and cuts engine torque as needed. Other systems control skids this way (and the Volvo has this so-called stability control, as well) but they monitor the longitudinal centerline, among other things.

By using brakes and engine torque, the RSC system induces understeer, forcing the car to "plow" straight instead of continuing on a sharp turn that will cause a rollover. I had faith in how this would work in the back and forth of a slalom course. My doubts were over the emergency lane change test — trying to avoid an object dead ahead at high speed. Would understeer not lead me straight at the thing I was carving sharply to avoid? Answers below.

And third, in the event of a rollover, the XC90's roof is reinforced with beams of Boron steel, reputed to be four to five times stronger than regular steel. Three-point seat belts are standard in all three rows of seating (third row is optional), and side curtain air bags protect all three rows, as well.

We didn't get to try out the Boron steel or the bags on the runway because we didn't come close to tipping a car over. We may have got an outside rear wheel to lift just a bit, but if it did, RSC slapped on the brakes, controlled the engine, and flattened us out again.

In the slalom, when I pushed the car too far, a noise that can best be described as "grinding" seemed to emanate from somewhere near the firewall. RSC at work. The car slowed, flattened itself, and was back under control. It would not allow me to feed it more gas. If I tried to force it to let up on the understeer, it would not do so until the car was under full control.

Yet, as to my fears about being hauled straight ahead into disaster in the emergency lane change test, they were unfounded. The induced understeer is so momentary that the car is righted virtually instantly and normal steering can then go on.

Sandy Stevens, owner of Stevens Advanced Driver Training, took the XC90 through the emergency lane change test at upward of 60 miles per hour with the brakes on, a move he calls "an extreme evasive maneuver."

"It wouldn't let me make a mistake," he reported in some wonderment. "Normal inside rear to outside front pitch was absent."

By that he was referring to what may be among the most deadly situations for SUVs. When a vehicle traveling at a speed too high for an emergency situation has to turn and brake suddenly, weight is transferred rapidly from the rear quarter of the car on the inside of the turn to the front wheel on the outside of the turn. As much as 80 percent of the car's moving weight can end up on that one wheel.

Properly executed in a car with ABS, the brakes are slammed on, putting weight on both front wheels. Then the turn is made. Improperly executed, the turn is made first (a natural if improper reaction). This instantly shifts weight to that one, outside front wheel. When the brakes are then applied a bad situation gets horribly worse as even more weight heads to that one wheel. The result: a rollover or a skid to curbing or soft shoulders and, also, a rollover.

The XC90 will not let this happen because it sets the car flat before control is lost, redistributing the weight to all four wheels.

There is more to be written, from a consumer standpoint, about the XC90. That will come when I get a week or so in one. This day's testing, in a pre-production model, was aimed only at evaluating its rollover protection system, which can only be pronounced stupendous.

It is a system that should find its way into all SUVs (Ford owns Volvo). And at prices ranging from around $34,000 for front-wheel-drive models to $43,000 for fully loaded all-wheel-drive models, the XC90 was selling out even before it hits showrooms in the weeks ahead. Already, the 6,600 cars planned for delivery in North America for November and December are gone. And there will be waiting lists for the 35,000 slated for US sales next year.

And, no, even though a photographer for the Globe kept telling me in jest (I think) that we'd make Page One if I rolled the XC90, I couldn't do it.

To which I can only say, "Thank DOINK for that."

This story ran in the Boston Globe on 10/12/2002.
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