Between Lowell and Lawrence, Mass., last Tuesday mid-afternoon, the temperature reached 102 degrees. By the time I got to Boothbay Harbor, Me., the thermometer had dropped 40 degrees. To my surprise, the price of fuel had dropped too. In my experience, gas is always more expensive where you’re going than where you’re coming from, unless you’re going to Indiana. At stations along the secondary roads in New York State, diesel fuel, which is what my pickup takes, was over $5 a gallon. In Boothbay Harbor, it was $4.79, and the lobster rolls were cheaper too.

At these prices, driving simply feels different. For one thing, the margins of America’s highways are turning into a used-car lot. If gas stays this expensive, grass will soon be growing through the floorboards of the Range Rovers and Suburbans I saw parked  for-sale signs in their windows  at the ends of driveways. I found myself wondering whether their fuel tanks were absolutely empty and whether, in fact, those vehicles wouldn’t be worth more as scrap steel  chopped and crushed and shipped to China.

What these gas prices really do is let you see through the illusion of shiny new cars. One of the basic automotive laws is that nearly every vehicle is losing value from the moment it’s driven off the lot. As traffic slowed, and fuel-mileage dropped, through Portland, Me., I looked out at the cars around me and could practically feel depreciation  economic rust  eating away at them, and at me too, and all the faster thanks to high gas prices. My pickup was dwindling in value even as the value of the fuel in its tank was going up.

It was a puzzle, really. It may have looked like we were all trying to get somewhere, there on I-295. What we were really doing was burning the gas in our tanks before it became too valuable even to think of burning. I filled up before I left Boothbay Harbor, of course: 24 gallons, $118. My plan was to get home before I couldn’t afford to. I had driven to Maine to speak at a conference named in honor of Rachel Carson. You can imagine how that felt.