We are partial to Audis for three main reasons: their superb all-wheel-drive systems, subtly elegant and ergonomic interiors, and optional continuously variable transmissions.

The A4/S4 lineup is at the heart of the Audi lineup. It includes about 20 variations, including four-cylinder, turbocharged engines, V-6s and V-8s, station wagons, sedans, front-wheel drive, all-wheel drive, and transmissions that include a six-speed manual and six-speed automatic. You can also buy one with a continuously variable transmission like today's test car, the four-cylinder turbo 2007 Audi A4 Cabriolet 2.0 T CVT.

Continuously variable transmissions have been around for decades, notably in snowmobiles. Using a combination of convex pulleys that open and close and let a chain or belt change its shape with virtually endless variety, it gets the most out of any engine (although really high-powered engines pose a challenge). But Audi has built the best CVT I've ever seen, with preset "shifts" that let a driver pretend to be driving a manual. And in a fine display of dual per sonality, the seemingly electric hum of the CVT in automatic mode gives way to racing-style upshifts and downshifts.

Which is not to say that the A4 with CVT lacks power. After all, our test car pulled 200 horsepower from just 2 liters. Owing largely to the small engine and CVT, that performance also results in decent fuel-economy figures: 27.1 miles per gallon in Globe testing.

From the outside, the A4 looks imposing, with a high hipline, headlights that rise and curve back into the fenders, and a looming grille that some do not like. Underneath are air intakes that house fog lamps and also help cool the front brakes. Despite the rather aggressive front, this really is not a large car. The rear seat room, in particular, can be pinched -- you wouldn't want to put more than two adults back there.

Inside, there is bold hooded gauge presentation and a center cluster of controls (some duplicated on the three-spoke steering wheel) that are easy to find and intuitive. Leather and combinations of wood or aluminum trim add to the fine sense of quality.

The drop-top cloth roof is well insulated and relatively quiet at high speeds. An optional roof with extra insulation is available.

On the road, the remarkable thing about the CVT is that you can truly drive it two ways: let the belts spin their magic and save fuel, or flick the paddle shifters in manual mode and play when the mood strikes.

Powered front seats with firm bolstering and lumbar support are standard. So too are antilock brakes, brake assist for emergencies, and stability control. Standard air bags include driver and front passenger thorax bags and head side bags. An anti rollover system senses if the convertible might be ready to tip over and deploys, explosively, roll bars. A ski sack, between the rear seats, is also a useful standard offering.

But, as you may have figured, the A4 is not an inexpensive car, starting at $39,100 and climbing to nearly $43,000 in our test model with the addition of upgraded sound, a wind deflector, 17-inch alloy wheels with all-season tires, heated front seats, and walnut trim.

With its 4 series, Audi has created a lineup that allows consumers to comparison shop within one manufacturer. That's an achievement in itself.

Royal Ford can be reached at ford@globe.com.