Revolution comes in increments. Take the current reign of the sport-utility vehicle, whose market position seems unassailable. First, there was the threat of the safety mavens, who said sport-utes were crushing cars on America's highways. The driving public wanted to be safe. Sport-ute sales went up. Then came the environmentalists, who said sport-utes were dirtying the air. Ford Motor Co., the nation's leader in truck sales, responded by producing the biggest sport-ute ever, the Excursion. Buyers are lining up to buy the thing at a price (to be announced June 21) that is expected to exceed $40,000. While the environmentalists were declaring Ford an enemy of the state, the automaker announced that henceforth, all of its sport-utes will meet or exceed the toughest federal clean-air standards. Ford's sport-ute sales went up. But now comes a real threat to the sport-utility empire, the worst kind of threat--a competitive, appealing product that does more than most sport-utes without having the safety and environmental problems of being one. It is the 1999 Saab 9-5 Wagon. Let us look at the car from the floor up. Most sport-utes have rear floors of limited utility. Rear seats fold down to expand cargo space, but that's about it. By comparison, the 9-5 Wagon's rear floor is a work of genius. There are standard CargoTracks, two Saab-patented floor-mounted aluminum rails with adjustable belts to hold cargo in place during panic stops or crashes. This is important. Many people who die in front-end hits actually are killed by rear cargo hitting their heads. There's also an optional sliding load floor, which can be rolled out nearly 20 inches and can support up to 440 pounds of cargo. It eliminates potentially harmful back bending when loading the rear, and can be used as a picnic table, too. When the 9-5 Wagon's rear seats are folded down or removed, available cargo space grows to 72.9 cubic feet, equal to or better than many compact sport-utility models. Cargo capacity is 37 cubic feet with the rear seats installed and up. Other useful cargo area touches include low loading height; a standard rigid, foldable and removable cargo shelf; and tailgate lights designed to illuminate the cargo area inside and outside of the car during night work. The car also drives nicely. I tested the turbocharged, four-cylinder, 170-horsepower version of the 9-5 Wagon and reveled in its ability to take curves with aplomb. I also had a blast passing lumbering six- and eight-cylinder sport-utes on straightaways, righteous in the knowledge that I was moving faster and more safely than they were, while spewing out fewer pollutants. I didn't crash-test the 9-5 Wagon. But some things are a matter of common sense. The wagon has a lower center of gravity than many sport-utility models, which means it has a lower tendency to roll over in crashes. Its body is engineered to absorb crash energy, impeding the rush of harmful forces to the passenger cabin. And there are front and side-impact air bags, as wel l as th ree-point seat belts on all seats, to help soak up the crash energy that reaches inside. In sum, the 9-5 Wagon is the perfect product to stem the growth of truck mania, which now accounts for 48 percent of all new-vehicle sales in the U.S. market. The wagon's effectiveness is not in any legislation or regulation. Its power comes from the same source that created the truck frenzy--the ability to give consumers what they want, perhaps to go beyond their expectations, at a competitive price. 1999 Saab 9-5 Wagon Complaints: None. This wagon is a winner. Praise: The 9-5 Wagon takes away almost every reasonable excuse for buying a larger truck. It hauls five people comfortably, it carries lots of stuff, and because it is front-engine and front-wheel-drive, it does not get stuck in the snow. True, it does not go "off road." But then again, neither do most of the four-wheel-drive sport-utility vehicles in the nation's mall parking lots. Head-turning quotient: It's a Saab--quirky, nerdy, attractive in a high-heeled, offbeat sort of way. Ride, acceleration and handling: Impressive in all three categories. Excellent braking. Brakes include power four-wheel discs with standard antilock backup. Engines: The test car came with the standard turbocharged 2.3-liter in-line 16-valve four-cylinder engine, designed to produce 170 horsepower at 5,500 rpm and 207 pound-feet of torque at 1,800 rpm. A turbocharged 200-horsepower V-6 is available. A five-speed manual transmission is standard with the four-cylinder engine, which can also take a four-speed automatic as an option. The V-6 gets a standard four-speed automatic. Mileage: With the tested four-cylinder model, about 27 miles per gallon, compared with about 15 mpg for the average compact sport-ute. Fuel capacity is 18.5 gallons of recommended premium unleaded gasoline. Estimated range is 485 miles on usable volume of fuel. Price: Base price for the tested four-cylinder wagon is $31,850. Dealer invoice on base model is $29,621. Price as tested is $34,925, including $2,500 in options (leather seats and automatic transmission) and a $575 destination charge. Purse-strings note: Compare with any compact sport-utility vehicle in any price range. It's a buy.