It was a midnight run. The road was clear. The moon was bright. Unseasonably cold winds whipped a late March night.

I listened to the engine of the 2008 Audi A5 3.2 Quattro coupe and thought about end times -- not in the apocalyptic sense, but denouement in the manner of the closing of an era.

Decades ago, when I began covering the automobile industry, drunk on cheap gasoline and high on horsepower like many of my colleagues, such thoughts would not have entered my mind. Back then, it was all about the thrill of the drive -- the faster, the better -- gasoline consumption and speed limits be damned whenever and wherever those restrictions could be consigned to perdition without causing bodily harm.

But I and the world in which I drive have changed over the years. I no longer believe in the infinite availability of finite resources and can't understand why I ever did.

My appreciation of the limits of things came with travel to Asia, Europe, Africa, South America and other places where people of different colors, religions, ethnicities and cultures all wanted the same thing -- more energy, be it from fossil fuels or their alternatives, to acquire personal mobility and to improve their lives.

They weren't begging for that energy.

They were, and are, demanding it. That made me realize that we in the United States, sooner or later, will have to change our attitudes about energy and how we use it.

But old habits die hard, which is why I was out on Interstate 66 at midnight, when I figured the traffic would be light, putting the wonderfully agile, seductively powerful all-wheel-drive A5 3.2 Quattro coupe through its paces. If there is such a thing as the perfect driver's car, I thought, this is it -- so light, tight, responsive.

Audi could have engineered the compact coupe to get more than 18 miles per gallon in the city and 27 mpg on the highway and to run on something other than premium unleaded gasoline. Certainly, that is something my older, more conservative, more responsible mind would appreciate.

Or would it?

I found a side road, blessedly free of traffic, and touched the throttle. Whoooosssshhh! The extra o's, s's and h's are there to give you a better idea of the smooth power of the A5 3.2 Quattro's 3.2-liter, 265-horsepower V-6 engine. It's not "whoosh," which is too fast and jerky. It's "whoooosssshhh" -- smooth, gentle, yet powerful.

The Whoooosssshhh Effect is a very powerful thing. If you experience it once, you want more of it, even if it means sneaking out of the house for a long midnight drive. You know it's wrong and that it could get you into trouble. But when you're caught up in the whoooosssshhh of the moment, as I was every time I got behind the wheel of the A5 3.2 Quattro coupe, with its "meteor gray pearl effect" exterior paint and its silky six-speed automatic transmission, you just don't care.

But all road trips end, as this one did. And it is on those homeward drives -- those eventual reconnections with reality, responsibility and consequence -- that the mind engages in conversation with the soul and questions previous actions. Should I have done that? Why did I do that? How long will I be able to continue getting away with doing that? When and how will this end?

I entered the house quietly and ducked into the place we call the "TV room" and closed the door. I turned to one of those foreign news channels, which featured stories about Nigerian officials worrying about attacks against oil pipelines and attempts in Iraq to defend against the same.

I turned off the TV, went to the bedroom and crawled into bed next to my wife.

"You still up?" she asked.

"Yeah," I said. "Just wondering if Audi will ever offer that A5 in the United States with diesel, or maybe a hybrid engine . . ."