Dear Tom and Ray:

I have a new Acura MDX with a display that shows the average mileage I get per gallon. The computer can evidently drive the car more efficiently than I can, because I get the best mileage when using cruise control. Being interested in higher mileage, I find myself using the cruise control whenever I can -- not just on the highway. Is it a good idea to use the cruise control sporadically, for short intervals? Am I overusing it or wearing it out? -- Peg

TOM: Are you overusing it? Yes. Are you wearing it out? No. The cruise-control mechanism itself should outlast the car, no matter how often you use it. But using the cruise control around town is not a good idea, in our humble opinion.

RAY: Here's why. Think about how you normally drive in town. You're going along, your foot is on the gas and up ahead, you see somebody walking toward the street between two parked cars. What do you do?

TOM: Is it my mother-in-law? Because that might affect my answer.

RAY: No. Assuming it's an innocent passerby, most of us would -- as a first step -- lift our foot off the gas pedal. That's the first thing you do when faced with an "unknown" situation up ahead.

TOM: Right. While your foot is off the gas, you're assessing the situation. And if you get closer and you're still not sure it's safe, your foot then goes to the brake. Or, if the situation becomes clear -- the person stops and makes eye contact with you -- you go back on the gas and continue.

RAY: But when the cruise control is on, you miss that crucial first step in safe driving -- taking your foot off the gas. This not only begins to slow you down, making stopping easier if necessary -- but slowing down also gives you more time to assess the situation. And we've found that in city or town driving, where there's much more activity on and around the roads, that extra step is critical for safety (which is why most cruise-control systems won't even engage below 30 mph).

TOM: Out on the highway, conditions are much safer. All of the cars are going in the same direction, traveling at pretty much the same speed; there are no intersections and no pedestrian traffic to worry about. There, the cruise control is safer.

RAY: So I'd confine my cruise-control use to the highway, Peg. The few pennies you save (by having the computer meter the gasoline more smoothly than you can by foot) aren't worth the safety risk. And if gas mileage is so high on your priority list, consider something other than an SUV next time.