RAY: This week's Puzzler was sent in by Joe Barger. He writes, "My father, Max, at about age 65 still likes to mow his own lawn with a gasoline push mower (not self-propelled). He's had the same mower for 20 years. About a year or so ago, he noticed that the mower was not getting very good gas mileage. The mower was using much more gas than it used to per cut of the lawn. So Max took the lawn mower to the neighborhood small-engine repair shop. They replaced a spark plug and spark plug wire, cleaned the carburetor, and installed a new air filter.

After all the repairs, Max took the new lawn mower home. But he noticed that the gas mileage had not changed a bit.

The engine and the lawn mower were in perfect working order. The lawn-mower service guys did nothing wrong, and there's nothing they overlooked.

TOM: The lawn isn't thicker than it used to be?

RAY: Nope. What's going on?

[ Car Talk Puzzler ]