It was guttural, yet buttery — rich, creamy, smooth. It stopped as quickly as it started. And when it started — on the abandoned early- morning rural roads where I tried it — it leapt, consuming the dash from 0 to 60 mph in barely five seconds. I did this repeatedly, but stopped upon realizing that pleasure had become abuse, perhaps dangerously so.

It was the 2012 BMW 650i convertible, priced at $105,025 with almost every conceivable option. It was more art than car, stunningly beautiful art, the kind that drew admiring crowds and got preferred spots in big-city parking garages with no request or bribe.

I likened my week in it to a hot affair, especially those pre-dawn romps along rural roads in Virginia, New Jersey and Upstate New York. Those were times of golden fantasy, enjoyable until the summer dawn arrived with its heat, traffic congestion and law enforcement. I slowed down and drove back home to my wife.

The 2012 BMW 650i convertible is more than a car, in much the manner that a Picasso or van Gogh is more than a painting. It will disappoint or offend anyone who does not understand that.

If you are looking for practicality, look elsewhere. Convertibles are inherently impractical automobiles. One that comes with a base price of $90,500 and nearly $14,000 worth of options is even more so.

The 650i is a rear-wheel-drive mid-size convertible with seating for four people. But as with most convertibles, the rear seats are cheeky appliances not really meant for anyone.

The car is fuel-efficient — as long as you are careful to distinguish between economy and efficiency. Economy speaks to cost. There is nothing economical about the 650i. Efficiency speaks to the amount of work done or pleasure given per unit of fuel consumed. Here is where the 650i convertible excels.

In redesigning the car for 2012, BMW increased the weight of the 650i convertible by 254 pounds (4,531 pounds, compared with 4,277 for the 2010-11 iteration). But the new car, with a shape reminiscent of an arrowhead at the front end connected to an indented shaft running along the side panels, is more streamlined, more . . . aerodynamically efficient.

BMW used a larger engine, a 4.8-liter V-8, in the 2010 model of the 650i convertible to produce a maximum 360 horsepower. Yet it gets a maximum 400 horsepower out of the twin-turbocharged 4.4-liter V-8 in the 2012 model.

Assuming that people spending the money for a 6-Series BMW convertible care about things such as fuel economy, the new convertible offers them a slightly larger car with more power at a marginal increase in fuel savings — for example, 24 miles per gallon on the highway in the 2012 convertible compared with 23 miles per gallon in predecessor models.

But all of this is sort of missing the point, which is that the 2012 BMW 650i convertible is expressly for grand touring — turning those long, leisurely, no-deadline, no-destination-in-particular drives into events in themselves. BMW’s patented Driving Dynamics Control optimizes suspension and engine characteristics for different driving styles at the push of a button. You can choose “comfort,” “normal” or “sport.”

I found that it all depends on mood, on the given road and on opportunity.

On long afternoon drives along the New Jersey Turnpike, I chose either the “comfort” or “normal” setting and settled into the cinnamon-brown Napa-leather womb of the 650i convertible in my possession. But on those pre-dawn back roads with their many undulations, twists and turns, the “sports” setting — tighter steering, quicker engine responses — yielded more fun.

And there were those rare times when all things were aligned to produce the perfect drive. The early morning was bright and crisp — an excellent climate for pushing a button on the 650i’s floor-mounted center console and automatically lowering its top. On other days when traffic was snarled on the interstates, it did not really matter.

Sitting in the 650i convertible is akin to sitting in a richly but tastefully appointed luxury hotel suite. Raise the top. Turn on the air conditioner. Enjoy an enlightening extravagance. Hard times hurt less with money and the things it can buy, the BMW 650i convertible being one of them.