Dear Tom and Ray:

I am a patrol officer. The squad cars we use run on compressed natural gas (CNG). Presently, there is some debate about whether running cars on CNG is good for the engine or not. The cars do seem to require a high degree of maintenance, although we are told that the cost of the CNG is a fraction of what the city would spend on gasoline. What do you guys think? -- Jim

TOM: Actually, Jim, CNG should be better for the engine than gasoline. It burns much cleaner and leaves behind a fraction of the carbon deposits after it's burned.

RAY: Not only would CNG produce less carbon in the engine, but since it burns cleaner, it creates less air pollution in the areas around city doughnut shops. (Sorry, Jim, that was a cheap shot. I apologize).

TOM: Seriously, Jim, because they burn cleaner, engines that use CNG should require less maintenance, if anything, not more.

RAY: So, you might be asking, if CNG is so great, why aren't more people buying CNG cars? Because there's no infrastructure to refuel them. Cities, towns or companies that have their own maintenance garages can install refueling stations, knowing that all of their vehicles are going to stay within a few miles of that station and be there to refuel every night.

TOM: The rest of us, unfortunately, can't take for granted that we're going to be passing by Frank's Compressed Natural Gas Station and Cigar Emporium just when the CNG runs low.