The $400,000 Dawn convertible, the newest car in the Rolls-Royce family is a big, beautiful boat.

Powered by a 6.6-liter twin-turbocharged V-12 engine that makes 563 horsepower and 575 pound feet of torque, and weighing in at just under three tons, it is a street schooner designed to sail the Cote d’Azur.

Meant stylistically to recall the 1953 Silver Dawn drophead – the first Rolls-Royce vehicle built as Britain began to recover from World War II – the new Dawn is long and broad in the beam, with graceful lines that suggest sinuous, sophisticated strength.

The Dawn was a driving delight – powerful and pleasantly understated.

Rolls-Royce calls it “a sumptuous and sartorial slingshot of wood and leather,” and says the slingshot will accelerate from zero to 60 miles per hour in about 4.9 seconds.

As if to underscore the vast strength of its V-12 engine, the Dawn (like other Rolls-Royces) features a “Power Reserve” gauge instead of a tachometer.

In an exploratory mood, I pressed the gas pedal down on a stretch of open road and watched the reserve drop from 90 percent to 10 percent. In short order, the Dawn crested 110 miles per hour without showing any sign of struggle, and without visible movement on the gas gauge.

(The Dawn gets about 19 miles per gallon when driven judiciously on the highway, and around 14 in the city.)

The acceleration is sure without being scary, and the drive experience is somewhat detached, creating a feeling of floating above the roadway. This motorcar is meant for old-fashioned motoring. With Vivaldi on the Victrola, and the Santa Ynez stables and vineyards sliding by, I was inclined to proceed slowly.

Rolls-Royce asserts that the Dawn is the quietest convertible ever built, and as quiet as its hardtop Wraith. It features a six-layer fabric roof that, when raised, creates none of the wind noise typical of ragtop cars. The mechanism that lowers and raises the roof is so soundless that Rolls calls it a “silent ballet.”

Everything about the Dawn is stately and silent. Even the slowest of the fan settings is marked “Soft” instead of “Low.”

With the top down, the drive is a little noisier, and the enormous rear passenger area – fine, leather-bound acreage that includes its own seat warmers and coolers – is as windy as the back seat of a lesser car.

But Rolls insists it is quite safe. “Should the worst of circumstances arise,” the company says, the Dawn will instantly deploy a concealed “roll-over protection system” to protect car and driver.

Mechanically, the Dawn is very much its own car, not a chopped Wraith or Ghost, not a shrunken Phantom. Rolls says that though it shares design themes with the three other cars in the company lineup, 80 percent of the parts are specific to the Dawn.

The interior appointments are heavy on select woods, leathers and chrome. The upholstery in the model I drove was clad in a supple, sensuous Mandarin Orange leather that seemed almost edible.

Audiophiles will be pleased to know Dawn’s designers have included “the most exhaustively designed automotive hi-fi system ever developed.” A hidden microphone senses ambient noise and adjusts volume and tone accordingly.

The Dawn is a two-door, but its builders insist it is far from the typical “2+2” convertible that, like the Ford Mustang, Chevrolet Camaro, Buick Cascada or other soft tops, has two seats in front and a cramped afterthought instead of a back seat.

Rolls representatives said the company sold 4,000 cars last year, a third of those in North America. Around 80 percent of its vehicles’ purchasers are “new wealth entrepreneurs,” Rolls reps said.