Power, technology spotlighted in BMW M6

Depending on how you look at it, the 2007 BMW M6 coupe and convertible cars pack a power punch or they're unfriendly gas guzzlers.

Sheer performance is impressive, with race car-like power coming from a 500-horsepower V-10 engine mated to a transmission with six or even seven gears. There's a bevy of high-tech equipment to maximize handling of these rear-wheel drive models, too.

The M6s are unfriendly, though, because despite having only four seats -- two of them cramped -- the cars' fuel economy ratings are on par with those of big sport utility vehicles, and greenhouse gas emissions put them in the federal government's "worst" category.

Some technology features designed to elevate the driving experience in the M6 can, instead, be downright frustrating.

For example, drivers need time -- and a tutorial -- to figure out how to work the Sequential Manual Gearbox (SMG) transmission for smooth shifts, and this is even when the transmission is in an "automatic" mode.

BMW officials aren't perturbed about the dual M6 personalities.

They know the low-volume, high-tech M6s are status symbols as much as driving machines and are the envy of car lovers.

Only well-to-do enthusiasts can afford an M6. Starting manufacturer's suggested retail price, including destination charge and federal government-required gas guzzler tax, is $101,995 for a 2007 M6 coupe and $108,695 for the 2007 M6 Convertible.

They compete with other performance-oriented, rear-wheel drive, two-door cars from Europe, such as the V-12 powered, 2007 Mercedes-Benz CL600 coupe with a starting retail price, including destination charge, of $144,975, and the 2007 Jaguar XKR Convertible with supercharged V-8 and a $92,500 starting price.

The M6 is from the race and performance unit of BMW, where "M" cars attract the attention of men -- yes, virtually all admirers are men.

Young and old, they noticed the test M6 Convertible during the test drive, even in a grocery parking lot. And they all swooned, despite the lofty price, and nodded knowingly when told about the M6's well-known meddlesome SMG seven-speed transmission. (A more familiar six-speed manual also is available.)

The M6 cars look different from other BMWs, including the 6-Series coupe and convertible on which they're based.

M6s ride like road-huggers on large, 19-inch, low-profile tires and have an aggressive M-styled front end and a loud, deep exhaust note that sounded, at times, on the test car like a brawny domestic V-8.

There was simply no way to travel quietly in the M6 Convertible. I heard the engine growl nearly all the time from the four exhaust tailpipes, and so did a number of nearby drivers and pedestrians.

At least the sound reminded me to check the M6 speedometer often, because I could get up over city speeds easily -- and by just using the first couple of the transmission's seven gears.

The sophisticated, 5-liter V-10 is new in the M6 Convertible for 2007, having been put in the M6 Coupe in 2006.

The powerplant puts out an impressive 100 horsepower per liter and peak torque of 383 foot-pounds at 6,150 rpm. The M6's V-10 even has a redline over 8,000 rpm, which is like a race car's, and the tachometer scale goes to 9,000 rpm.

It's no surprise, then, that the government fuel economy rating is low at 12 miles a gallon in city driving and 19 mpg on the highway for the convertible.

This is about the same fuel mileage rating as a 2007 Cadillac Escalade with all-wheel drive.

And one tankful -- 18.5 gallons -- of the M6's required premium gasoline these days costs more than $50. It went down like water in the test vehicle which didn't even get 12 mpg in combined city and highway travel.

Brakes had immediate stopping power and fast response, and steering was quick, too.

The test M6 Convertible had the optional-for-$1,000 head-up display that showed the car's speed, as well as tachometer information, on the lower part of the windshield. Thankfully, I didn't have to glance down into the instrument cluster to monitor my speeds.

But oh, I felt as if I was creeping along the pavement in the M6 in my neighborhood. The sense of speed is deceptive. Even on highways, I jumped up over speed limits before I knew it and had to back down quickly.

Thankfully, BMW provides an M driving school at its Spartanburg, S.C., facility so buyers get a chance to experience the real capability of the M6.

U-turns were difficult. The turning circle of 41 feet is more like that of a pickup truck.

The M6 comes with BMW's iDrive system, which allows drivers to tailor a long list of comfort and drive settings in the vehicle via a large knob in the center console and a series of menu screens on the dashboard. However, iDrive continues to be cumbersome to maneuver through, and it takes regular referrals to the M6 owner's manual to figure it all out.

Front seats in the M6 Convertible are among the best in the industry as they're roomy, well-shaped and eminently adjustable.

The two, small back seats, on the other hand, aren't for adults and not exactly inviting for children, either.

At least the M6 Convertible trunk is decently sized, with 12.4 cubic feet of cargo room with the fabric top up on the car and 10.6 cubic feet available when the power-operated roof is down and stored.

All safety equipment is standard on the M6, including front, side and head protection, stability control, traction control and even automatic brake drying.

Consumer Reports does not rank the M6s separately, but it recommends the BMW 6-Series line. Predicted reliability is "average."