Q We just bought a 2010 Camry and read about the problem of uncontrolled acceleration, which Toyota has attributed to floor mats getting caught under gas pedals. I recommended a two-step strategy to my wife, just in case. If we are on the highway, I believe the safest driving area is the inside lane because you could use the shoulder to pass other vehicles. This is where my brother the cop disagrees with me.

My opinion: If you cannot slow the vehicle by applying the brake, turn off the ignition, because you can still steer without power steering and the engine will slow down the car as you apply the emergency brake. The cop says to wipe out the concrete barrier or other cars driving next to you to slow down the vehicle. What is your opinion?

A I'm always stunned to hear of crashes caused by "unintended acceleration." We could debate whether the phenomenon truly exists, but the real issue is what to do if it happens to you. The answer: Turn the ignition off. The brakes and steering will still operate, although more physical effort may be required. The ignition switch cannot be rotated to the "lock" position unless the shift lever is placed in Park, so it is not possible to lock the steering in this situation. By shutting off the engine, the acceleration factor is eliminated completely.

The other option is to shift the transmission into Neutral and allow the engine to continue running. Most modern engine management systems will bring the engine rpm to 4,000 while at full throttle in Neutral or Park. In this scenario, the power assist will still be available for both the brakes and steering.

Hitting objects or other vehicles is completely wrong. Why put yourself and others at unnecessary risk?

Q I am thinking of purchasing a four-wheel- or all-wheel-drive passenger vehicle. I have several concerns you may be able to clarify. At 4,200 pounds and 252 horsepower, is the Buick LaCrosse underpowered? Over a period of years, would the engine wear out sooner than it should? Would the fact that it is AWD wear the transmission and drivetrain more quickly? Is it true that with this type of all-wheel-drive system, if you replace one tire you should replace them all?

A No, a 4,200-pound vehicle with more than 250 horsepower is not underpowered. With today's technology, virtually every new motor vehicle has more than enough power for daily driving and routine loads. The engine and drivetrain will not be overstressed and wear out prematurely. And absolutely, yes, with any four-wheel- or all-wheel-drive vehicle, all four tires must be the same diameter to avoid mechanical stress on the drivetrain.

If you replace just one, make sure to measure its rolling diameter to ensure it matches the other three. Mark the exact bottom center of the tire and its position on the pavement. Roll the vehicle forward exactly one tire diameter -- until the mark is again at the exact center bottom of the tire -- and mark that spot on the pavement. Then measure the distance between marks on the pavement, repeat the process on the other tires and compare measurements. All four measurements need to be the same to prevent stress and potential damage to the drivetrain.