We have to judge the Murano's zoominess by how quickly it passes road markers and pavement stripes, because inside you get the sensation that the engine isn't revving very quickly at all. When you stomp the accelerator in the Murano, it feels like it stays in one gear all the way until you've reached terminal velocity.

That sense comes directly from the CVT, which is an automatic transmission without gears. Engineers call these transmissions quot;stepless.quot; When you accelerate, instead of the conventional upshifting from lower to higher gears, the transmission has variable-diameter pulleys that act like variable gears without teeth, and change ratios continuously. A complex steel belt is squeezed between the pulleys and transfers engine torque to the driveshafts. The CVT quot;shiftsquot; ratios smoother than a normal automatic transmission, and allows the engine to rev at a speed that's most efficient for acceleration. The efficiency of the CVT also adds to the outstanding fuel economy of the Murano: an EPA-estimated 20/24 mpg city/highway.

The CVT is not a new device. Subarus, Hondas, and Nissans have used CVTs for more than a decade. Called the Xtronic, Nissan's new unit is similar to Audi's CVT in its ability to handle a lot of torque. The Audi unit, however, is tuned to shift like a conventional automatic, with six separate gear-like ranges. The CVT in the Murano, however, comes with just three ranges: D for normal driving, S for sportier acceleration, and L for the highest ratio, or lowest quot;gearquot; range. Shifting from D to S raises engine revs 2500 rpm. Dropping from S to L increases engine speed by another 1000 rpm. Rev the engine near its 6600 redline and the ratio automatically reduces, thereby lowering the engine revs as the Murano's speed increases. In short, the CVT is more efficient than a normal automatic transmission, and therefore acceleration is quicker than with a conventional automatic.

Engine braking is programmed into the electronics that control the CVT, so when you're coasting down a steep hill, accelerometers sense this condition and increase the effective gear ratio, which is akin to downshifting a conventional transmission.

Every operation of the CVT happened smoothly and silently during our lengthy test drive in the Vallecito Mountains in southern California, and during acceleration we kept our eyes glued to the Murano's tachometer to get a better idea of what was going on in the driveline. We were particularly impressed with the silence of the drivetrain. The variable pulleys that are the heart of the CVT must squeeze a flexible steel belt with tremendous force to prevent the belt from slipping, and the pump providing this pressure made no discernable noise during our drive.

The smooth and powerful drivetrain captured our attention first, but after several hundred miles of winding mountain pavement, the handling of the Murano also impressed us. The steering feels quick during turn-in, increasing your confidence that the Murano will corner like a sport sedan. It does just that up to about 8/10ths of the level you would drive an Altima sedan, and then it begins to understeer. The big 18-inch tires refrain from squealing until you're truly at the edge of cornering ability, which also adds to your confidence.

The all-wheel-drive system drives the front wheels until wheelspin is detected, then an electrically operated clutch pack automatically feeds up to 50 percent of the power to the rear wheels. Nissan