The Ford Explorer has been wildly successful, selling 5.5 million units since its appearance in 1990. This popularity probably exceeded even the most optimistic forecasts for the Explorer when it was launched, but Ford's midsize sport/utility matched the exact right characteristics to market conditions of the time.

The Explorer's combination of rugged looks, family-friendly capacity, and light towing capability struck just the right chord in 1990, and as consumer expectations increased through the decade, so did Explorer's ability to meet them.

Since then, the world has changed, with ever more capable competitors arriving on the scene, which, by late 2004 made the prior Explorer look like nothing special. Worse, the very ground under the Explorer's feet was becoming unstable, with higher gas prices and a cultural shift away from SUVs.

For 2006, Ford has shored up Explorer's weaknesses and exploited its strengths, but only time will tell whether the age of the SUV is truly coming to an end. Sales for the medium-size traditional-SUV segment were down 25 percent in the first half of the year, according to Christine Feuell, SUV group marketing manager for Ford.

Taking a bite out of the hide of Explorer and its cohorts is the car-based crossover-SUV segment, which gives sport/utility drivers most of the capabilities they actually use, with better ride, handling, and fuel economy.