Dayton Daily News

Dear Tom and Ray:

Guys, what's the big deal about plug-in hybrid cars? I've read that various automakers plan to come out with plug-in hybrids in the next two to five years. Isn't a plug-in hybrid just a current hybrid (like a Prius) with a battery charger? Is there some additional technology here that I'm missing? — Bob

RAY: Well, I guess you COULD put it that way, Bob.

TOM: But if I were to simplify it, I'd say that today's gasoline-electric hybrids use electricity to supplement a gasoline engine, whereas tomorrow's plug-in hybrids will use a gasoline engine to supplement electric power.

RAY: Cars like the Prius have enough battery power on board to power the cars up to 15 or 20 miles per hour and, after that, to assist the gasoline engine when necessary. That improves gas mileage significantly. You get twice as many miles per gallon as the average car, which is great.

TOM: But the Prius' batteries regularly need to be recharged by the engine (they never get plugged in), so the gasoline engine still has to run pretty frequently.

RAY: Plug-in hybrids alter the balance. They carry a lot more battery power, and use the batteries to do much more of the work of moving the car. And instead of constantly needing to be recharged by the engine, they get most of their recharging by being plugged in at night.

TOM: So, it's not just the recharge-ability; it's that plug-in hybrids will store a lot more energy on board. That's also why they're not available yet. We're waiting for a new generation of batteries to be ready.

RAY: Current hybrids use nickel metal hydride batteries (NMh). That was an improvement over the first hybrids, which used a boatload of Eveready D-cells. But NMh batteries are still too big and heavy for practical plug-in hybrids.

TOM: Within the next few years, carmakers are anticipating the mass production of lithium ion batteries (Li), which are far more dense. Sort of like my brother.

RAY: I'm a different kind of dense.

TOM: In the case of batteries, "more dense" means they store more energy in a smaller package. So, with lithium ion, instead of having to fill the entire back seat of a Prius with batteries, they can make a plug-in hybrid that maintains the interior room people expect in a family car without weighing the thing so far down that it's too heavy to be moved by its own batteries!

RAY: Perhaps the greatest advantage of plug-in hybrids, however, is that they'll allow us to address our oil use and pollution by focusing on a relatively small number of power plants, rather than on 100 million individual cars.

TOM: Right. So, once cars run primarily off of the electrical grid, we could add wind power, solar power, nuclear power, cow flatulence or anything we want to our power grid, while retiring dirtier, less-efficient plants. If we follow through with that, plug-in hybrids would be a great step toward energy independence and reducing pollution.

Inactive car still good to go

Dear Tom and Ray:

My rich old auntie recently shed this mortal coil and left a 1996 Toyota Camry Collector's Edition with 14,000 miles. Other than making only spotty trips to the liquor store, the car has not been used for the past two years. It is a luxurious car, for sure, but would I be asking for trouble because of its inactivity? — Annie

TOM: Gee, when my aunt died, all I got was a set of gas-station dinner plates. You, on the other hand, have struck pay dirt, Annie.

RAY: This is an excellent car, and we see many of them in the shop with 150,000 or more miles on them still going strong. So I think you'd do very well to weasel it away from any other covetous siblings who are eyeing it, and pounce.

TOM: If the car's been used occasionally during the past two years, that means it runs, which is great. So there's no concern about internal engine parts sticking or rusting together.

RAY: Unlike, say, your heart muscle, engines don't weaken when they sit around. In fact, the less they're used, the longer they last. My brother's got a bunch of old cars. The only reason they still run is that most of time he can't get them started.

TOM: The only parts that DO wear out over time, even if you don't use them, are rubber parts. Rubber is broken down by the ozone in the air. So, even though the tires have only 14,000 miles on them, they've been deteriorating for a dozen years now and should be replaced. The same is true for the belts and hoses, including the timing belt.

RAY: But for $1,000 or so, you can get all new tires, belts and hoses, and have, essentially, a brand-new car that'll last you for many, many years. And for an extra $50, we'll call your siblings and assure them that it's junk.

Send your comments or questions for Tom and Ray to: Car Talk Plaza, P.O. Box 3500 Harvard Square, Cambridge, MA 02238. Listen to them Saturdays at 10 a.m. on 91.3 FM or 88.5 FM.