There’s only one version of the 2006 BMW M5 on sale and it’s pretty much loaded with features straight from the dealer. Your $81,895 (including $695 destination and handling) not only gets you what might be the most incredible sedan in the world, but also some out-of-this-world standard technology. You can, however, add more than $10,000 in options, from the mundane to the marvelous. Among the workaday items are a power rear sunshade with rear manual side window shades for $575 and a folding rear seat for $475. A little less boring is Sirius satellite radio for $595. And another $350 gets you (or, rather, your lucky passengers) rear seat heating. If you really care for the people you cart around, you might also spring for the rear door-mounted side-impact airbags for $385. Now, with a concurrent jump in price, we move to the more interesting optional equipment. Comfort Access ($1,000) is not new technology and is offered by other manufacturers, but it’s still great. It eliminates the need to fish the key out of your pocket to unlock the vehicle, to start it (just push the ignition button), or to lock it (just touch the door handle as you walk away). The car senses the key in your pocket and takes care of everything.

A head-up display is not new or exclusive either (you can find it in Chevrolet products, for instance), but in the M5 it gets special treatment. The $1,000 system projects a color image onto a six- by three-inch field above the dash on the windshield, so you don’t need to take your eyes off the road. It can be programmed to show speed, navigation instructions, or cruise control settings. Or you can go wild and activate the virtual tachometer in rainbow colors with flashing upshift indicator. It’s clear even in the brightest sunlight, though we discovered that polarized sunglasses dull the display by about 50 percent.

If you’re already spending eighty large on a car, what’s another $3,500 for the pleasure of a full leather interior and the Alcantara (faux suede) headliner? The combination of materials makes the cabin feel like a box handmade by Italian artisans for holding your Rolex.

The most bang for your buck, however, is with the M Multi-function Sport Seats with Active Width Adjustment ($1,900). Don’t let the technical name fool you, these babies are more thrilling than a new Paris Hilton video and are the stuff of which myths are made. When Active Width Adjustment is activated, the seats respond to cornering forces by enlarging the side bolsters to keep the driver and passenger level. So in a right turn the left bolsters automatically expand and prevent you from being tossed around the interior like a rag doll. You can adjust the rate of response from Comfort to Normal to Sport. In Sport, the action is quite aggressive and the first time we felt the system working it took us by surprise. It was as though a Bulgarian masseuse had snuck into the back seat and decided to attack our midriff in mid-maneuver. Once we knew what it was, though, we couldn’t get enough and anybody who took a ride with us couldn’t get enough either. It makes JFK’s shenanigans seem dull in comparison.

In addition to these goodies, there are many safeguards built into the M5 to ensure that your first drive in a car of this caliber is not your last. Up to eight airbags are placed strategically throughout the cabin, the battery and the gas tank are designed to disconnect in the event of severe crash and, when it rains, the brake rotors are automatically dried by the pads to remove excess water. There’s also something called Slip Control, which disengages the clutch for a split second should a downshift on a slippery road threaten the sedan’s stability and, to bring the M5 down to earth without event, immense, ventilated disc brakes measuring 14.7 inches in front and 14.6 in rear.