Do you think the new cars of 1987 were better than the new cars of 2006?

We didn't, either.

But in at least one meaningful measure, we were wrong.

That measure is fuel economy, and, surprising as it might seem, based on the average gas mileage of all models, new vehicles sold in America during the penultimate year of the Reagan Administration actually traveled more miles on one gallon of gas than did cars sold in 2006.

In fact, 1987's average of 26.2 miles per gallon (mpg) is the highest annual average on record.

But 1987 might not be able to make that boast much longer.

The federal government predicts 2007 models will average 26.4 mpg.

It's about time, you might well contend. That's a valid point. After all, most consumer products are better or at least more technologically sophisticated today than they were in 1987. We didn't even have the Internet in 1987. Or the IPod.

But that 26.4 mpg figure is significant. It shows what carmakers, both domestic and foreign, can do even when, from an engineering standpoint, the odds are, literally, stacked heavily against them.

If you're designing vehicles and your goal is to make them go farther on a given amount of fuel, your most ruthless enemy is the pound. In 1987, the average weight of a vehicle sold in America was 3,220 pounds. The average weight in 2007? About 4,150 pounds.

This corpulent trend is hardly shocking, of course. Brawnily built four-wheel drive sport-utility vehicles and pickup trucks are vastly more popular today than they were in 1987. Such vehicles, which outweigh their car counterparts by an average of about 1,150 pounds, accounted for 50 percent of sales in 2006 almost twice the rate of 1987 (28 percent). As for four-wheel drive, an amenity that also lowers gas mileage, 29 percent of new vehicles sold in 2006 were so equipped, compared with 10 percent in 1987.

Some of the weight gain has gone to good causes, too. Safety features, chief among them the proliferation of air bags, add pounds to every vehicle.

The bottom line is that automakers have figured out how to build vehicles that weigh more in large part because they are safer and more comfortable to drive and ride in, but that burn less fuel and spew fewer pollutants into the air.

The carbuilders' accomplishments over the past two decades bode well for the future. The trend toward fuel thriftiness of course helps drivers, who face the prospect that gas prices will stay near the once unthinkable $3-a-gallon level.

But we're even more optimistic about the engineers' ability to lead us into an age when the production and burning of fossil fuels, and the potentially devastating problems that result, will seem as archaic as the horse-drawn buggy.