Question - My husband is buying a new Ford pickup. He wants to buy a diesel engine because he says it's more fuel-efficient, will last longer, and is less polluting than gas. I don't know about the first two, but I find the last argument hard to believe, especially since diesel fuel stinks so badly. Can you clear the air for me? - Alice

RAY: I don't believe for a second that he's interested in reducing global pollution either, Alice. We both know he just wants a big, honking truck. But we'll address the pollution issue anyway.

TOM: It's somewhat complicated. Diesel fuel is just one step more refined than primordial ooze. In fact, you can usually see mud, sticks and leaves in it as you pour it into your car. But since diesels operate at a much higher temperature than gas engines, some types of pollutants are reduced.For instance, diesels produce half as much carbon monoxide as gasoline engines.

RAY: On the other hand, diesels produce twice as much hydrocarbon emissions, four times as many nitrous oxides and five times as much particulate matter (a k a soot).

TOM: In their favor, however, diesels do seem to deteriorate less (in terms of how much they pollute) over time. So while gasoline engines pollute significantly more as they get older, diesel engines start out bad, but, in their defense, don't get much worse.

RAY: That's what my mother says when she's asked to praise my brother.

TOM: But despite that, I still come down firmly against diesels. As the owner of a convertible (a '63 Dodge Dart), to me there's nothing worse than driving behind one of those stinky, disgusting, particulate-belching ash cans. Actually, there is something worse: getting stuck in traffic behind one!

RAY: And I share my brother's bias. Not because I drive convertibles, but because I do occasionally drive with my window rolled down.

TOM: And as I said, cutting down on pollution has nothing to do with why your husband wants a diesel, Alice. He has MDE - Male Diesel Envy. Diesel engines appeal to guys' "survivalist" instincts. Diesels work by compression only, so they don't need electricity or spark plugs. Therefore, they - theoretically - will still run in the aftermath of a nuclear attack.

RAY: And that's probably what appeals to your husband. After Armageddon, he thinks he's going to be riding around in this Ford pickup, helping himself to the latest movies on video (which used to be all gone by the time he got to the video store, when there were still other people on the planet).

TOM: A lot of diesel engines do last a long time. They are durable, and they do get pretty good mileage. But they're also noisy, slow, stinky and hard to start in very cold weather. And, in my opinion, that far outweighs their advantages. But I can tell you've got no chance of talking him out of it, Alice, so buy yourself a good set of nose plugs and matching ear plugs -- and good luck.