Car Talk

Q.

I have a 2012 Toyota RAV4 with keyless entry and keyless ignition. If the battery in the key fob dies, and I'm not at home where I can grab the spare key, how do I start the car?

A.

Great question. There's not just one great answer, but I can give you a bunch of options.

First, look closely at your key fob. Many key fobs hide a temporary, pull-out key inside the key fob case itself. It's there for just such an emergency. Then you just have to figure out where the hidden keyhole is. A number of cars hide a keyhole in the driver's door handle. There's often a cap that you can pop off with the key, and then use the key to unlock the door.

Inside the car, a few cars have a hidden keyhole to start the car, too. Check your owner's manual, which often is hidden in the glove compartment.

If you don't have a hidden key in the key fob, your car may be one of those that now come with "remote services." In that case, call the manufacturer's help or roadside assistance line, and if your car is connected, they can unlock the car for you remotely.

No remote services? Try holding the key fob right up against the door near the handle and pulling. Sometimes there's just enough juice in the battery to allow you to unlock it from a close distance.

Or, if you're stuck in a parking lot or shopping center, you might be able to swap out the battery. Ask a good Samaritan to loan you the battery from his or her key fob for a minute.

That'll get you into your car and let you start the engine. Once the engine is running, it won't shut off when you give back the battery. That'll get you home, or to a place where you can buy a replacement battery.

If you can get into the car, and you don't have a backup key, there are ways you can start the car with a dead key fob. Try using the key fob itself to push the start button (touch them together). A bunch of manufacturers have a backup system built into the start button to allow a car with a dead key fob to start that way (I believe your Toyota is one of them.

Other cars have another spot where you can touch the dead key fob that allows the car to recognize it. We saw one that had you put the key fob at the bottom of the cup holder. So check your owner's manual.

If none of those ideas works, call your favorite roadside assistance company, and see if they'll bring you a key fob battery. Or, if not, maybe a brick.

You also can consider prevention. A key fob that works only at a closer and closer distance is one that's got a weakening battery. So is a key fob that requires multiple tries to get the door to open. If you notice these symptoms, change the battery.

You also can make it an annual habit. For less than 10 bucks, you can get a two-pack. Then every year on your wedding anniversary, change your battery and your spouse's battery. Nothing says "I love you" like chocolates and "I changed your key fob battery, darling."

Q.

I got into a discussion about engine life. I said, all things being equal, an eight-cylinder engine will last longer than a four-cylinder engine. My logic is that the more cylinders you have, the less often each cylinder will fire. Does this make sense?

A.

Uh, how best to put this? No.

No matter how many cylinders you have, every cylinder fires once for every two rotations of the engine's crankshaft. So if a four-cylinder engine and an eight-cylinder engine both are idling at 800 rpm, in one minute, every cylinder will fire 400 times.

Think about walking your dog: The dog's got twice as many legs as you have, but even if his legs were as long as yours, he'd still move four legs for every time you moved two ... assuming you both were going the same speed, and he didn't stop to lift one of his.

That said, there are some ways in which you could be right (I'm trying to bail you out here). Larger engines will generate more torque. That allows the use of a transmission that lets the engine run slower for the same given car speed. So while a four-cylinder engine might turn at 2,500 rpm at 65 mph, an eight-cylinder engine might turn at 1,800. That could contribute to longer life.

Also, if a four-cylinder engine is too small for a given car (if you had a 115-horsepower four-cylinder engine in a three-ton Chevy Suburban), the engine would have to work harder and run hotter to move the vehicle around. And that certainly could shorten its life, compared with a more appropriately sized larger engine.

But assuming an engine's power is appropriate to its car's weight (which is true in almost all cases these days), there's little to no advantage to having an engine with more cylinders.

In fact, there are some disadvantages. First, you're adding the extra weight of the bigger engine itself, so some of the power of the engine now has to go to simply moving that bigger engine around with you. And you could argue that an eight-cylinder engine has more parts that can break: more spark plugs to change, more valves to burn out, more valve guide seals to fail, more rings to wear out.

And we're big fans of getting the right-size engine for the car. With the enormous improvements in power per cylinder in the past decade, eight-cylinder cars are increasingly going the way of the dodo, and the vast majority of gasoline-powered cars will be running on four or even three cylinders soon.

Got a question about cars? Write to Ray in care of King Features, 628 Virginia Drive, Orlando, FL 32803, or email by visiting the Car Talk website at www.cartalk.com.