VW trotting out new models - and new management; Quantum, going in for Dasher, seeks sales leap

It's bigger, heavier (slightly, that is), yet much more fuel-efficient than the car it succeeds. The Volkswagen Quantum, replacement for the Dasher, is a low-drag vehicle that performs far better than the name may suggest. Indeed, what's a quantum? Unless the driver is of a scientific bent, he may have no idea of what the word means or who Max Planck was - father of quantum physics.

No matter, he doesn't have to recognize the name to drive and appreciate the car. What it shows is VW's deepening plunge into the fields of aerodynamics and high tech. Further, it shows the great distance the company has come since the days - not so long ago, really - of the air-cooled flat engine and the long-running beetle.

The Quantum (like the Dasher before it, a ''different'' kind of name for a car) is 120 pounds, or 5 percent, heftier than the Dasher, yet the combined city-highway federal fuel mileage rating is 33 miles per gallon - an 18 percent improvement over the ''D.''

The Quantum comes in three basic body styles - 2-door coupe, 4-door wagon, and 4-door notchback sedan - although the sedan won't hit the road till spring.

The base price is more than $10,200, although most Quantums are expected to go out the dealership door at $12,000.

Despite the price, VW looks for 20,000 Quantum sales in 1982.

What makes this model better than the Dasher? Largely, it's the ride. While the new car has a wheelbase 3 inches longer than the Dasher, a track 3 inches wider, and another three inches in width, it's the new independent rear suspension - a twist-beam rear axle with asymmetric bonded rubber bushings in the pivot points that, according to the VW engineers, prevents the rear wheels from understeer - which sets the car apart.

Try it on some of the twisting mountains roads, such as the Pennsylvania Poconos, where VW unveiled its new-model cars a few weeks ago. The ride and the driver control of the vehicle come through strong.

Nor was the aerodynamic shape of the car of low priority to the VW team back in Wolfsburg. Low drag - a measure of the slipperiness of a car as it cuts through the air - helps to raise m.p.g. To show just how sticky the VW design/engineering team was in organizing the car, the outside rear-view mirror is attached to the A-piller triangle, not to the door. The pillar-mounted location was determined in the VW wind tunnel in Wolfsburg, not only for aerodynamic reasons but also to help keep the side window clear in bad weather.

Handling, as expected, is extremely good - taut and sure. Simply, the car forgives the mistake-prone driver, up to a point.

The gearbox is silky-smooth and the performance lively. After driving the car for scores of miles in the Poconos, we can only say that we like it.

The West German automaker also has a brand-new Scirocco, plus a diesel-engine option for the Vanagon, a streamlined ''box on wheels.'' The Scirocco has a body 10 inches longer that is more wedge-shaped than the car it succeeds, with 12 percent better fuel economy on the road. In a 300-mile drive on the Interstate system, I chalked up an average 37 m.p.g. In beauty, the '82 version of the nameplate takes the cup over the mid-'70s design of the car it replaces.

Equipped with the Formula E gearbox and upshift light, the new-model diesel-powered Rabbit drove off once again with the Environmental Protection Agency's mileage bouquet for the fifth year in a row. Overall mileage is rated at 50, although some drivers report 55 and even more.

The fuel-conserving E-light, in fact, is standard on all manual-drive VWs except for the Vanagon. It shows the driver how to perform with economy in mind; in other words, with a light foot on the accelerator and an eye on the light.

What it does, according to VW, is be a fuel-saving aid without penalizing the performance of the cars.

Meanwhile, Webster's Third International Dictionary defines the word quantum as ''quantity'' or ''amount,'' as in ''the quantum of proof needed.''

VW engineers, as well as the people who count the money in VW's bank account, hope the new Quantum is proof of good driving.