Controllability

It makes sense that auto manufacturers usually design cars to understeer.

After all, natural human instinct tells everyone to slow down when a car won’t

go around a curve. This is appropriate for a car that understeers; but in a car

that is inclined to oversteer, the driver must do the exact opposite. That is, if

I have entered a corner far too fast, perhaps because the corner appeared to

be more gradual upon entering and then become a much tighter bend than I

had anticipated (this is known as a decreasing radius turn), then as the back

end of the car swings out on me, I will lightly press the accelerator to transfer

weight back onto the rear wheels of my rear-wheel drive car in order to

regain traction and try to save the situation. For most people, pushing down

the gas pedal when they have found themselves going too fast is counter-

intuitive — yet it just might save the day in an oversteer situation.

So understeer is better, then? Not quite. It is nearly impossible to modulate

the brakes of a car to effectively steer by braking. However, a skilled driver

can change the car’s trajectory by easing on and off the throttle, allowing an

oversteering car to receive inputs from two sources — the steering wheel and

the gas pedal.

A car that lets go at all four corners simultaneously (one that is “neutral” in

handling character) is considered perfect. That said, a car that is decidedly

neutral under one set of road and weather conditions might veer off into

understeer or oversteer as conditions change. The perfect solution would be

to have the perfect driver — one that could recognize and cope with whatever

handling attitude his or her car takes. However, most drivers turn into Elmer

Fudd in an emergency, not James Bond, so understeer is the rule of the day for

auto manufacturers, insurance companies, and product liability lawyers.