It's hard to believe it's been just a dozen years since the first modern minivans hit the market. Since then, they've revolutionized the auto industry and largely replaced that mainstay of the "Leave It To Beaver" era, the station wagon. During this relatively short span, a flood of minivans has come, and a significant number has gone. That includes the Dustbuster-like APV models from General Motors and virtually all the original products from Japan. It's surprising that the normally creative Japanese have had so much trouble figuring out the formula for a successful minivan. Their products have been too small or too tall, underpowered or just plain strange in a niche where utility, function and safety are the guiding principles. It looks like Toyota is about to finally crack the code with Sienna, its third-generation minivan due out this fall. Sienna will, in many ways, be a clone of the ever-popular Chrysler minivans, the market leaders and style-setters. Perhaps more important, it will be American-made, and that has both political and economic ramifications. But some minivan fans aren't all that enthused about the arrival of the Sienna. There's a small, but loyal, following for Toyota's current entry into the market, the Previa. And with good reason. The Previa's spaceship-shaped package is quirky, but far more functional, lavish and well-mannered than other Asian imports. True, the price tag of the Previa is high for the segment. But it is a Toyota, which means rugged reliability. And that's an important attribute in a vehicle that's bound to see use as the family bus. So, while it's tempting to dismiss a product entering its last year of life, the Previa is worth one last look. Available in both DX and LE editions, we chose the upgraded LE with the All-Trac full-time All-Wheel-Drive system to test.