Let's get this out of the way right now: I will declare a winner in this, my first comparison test. No thumb-twiddling that the winner "depends on what you like." The winner doesn't depend on what you like; it depends on what I like. Since that's simple enough to figure out, and you're smart enough to ascertain if my priorities are in line with your own, let's get on with it.
As debut comparison assignments go, this one's a goodie. Our subjects are three four-passenger convertibles priced at about $100,000: the $95,000 Jaguar XKR, the $104,000 Porsche 911 Carrera S, and the $115,000 BMW M6. Our venue is Miami Beach, a place uniquely suited for objective consideration of six-figure sports cars. Why? Because nobody there is impressed by six-figure sports cars, so adulation from the proletariat doesn't figure into the decision.
The powertrains in this trio are about as different as you can find in three cars that are angling for the same buyers. We've got a 355-hp flat-six, a 420-hp supercharged V-8, and a 500-horse V-10. We've got a six-speed manual, a six-speed automatic, and a seven-speed sequential manual. A sports car's powertrain is its soul, so it's not surprising that these cars all exhibit distinct personalities based on their power delivery. The Jag is a mellow bruiser, a well-dressed muscle car. The BMW is the techno track slayer, and the Porsche is the deceptively uncomplicated, deceptively quick traditionalist.
Of course, most of the time in south Florida, horsepower is less relevant than star power. If you go where the beautiful people are--in Miami Beach on Collins Avenue and Washington Street (not so much Ocean Drive, which is packed with tourists and rental cars)--you'll be taking your time.
The Jag is the most comfortable in this role. It's got buckets of low-end torque and a ride like a maglev. Its six-speed paddleshift automatic is fantastic, ripping off throttle-blipping downshifts that echo off the walls of the high-end boutiques on Collins. Put it this way: the Jag's automatic does a better job of impersonating a sequential manual than the M6's sequential manual does of impersonating an automatic.
The M6 is a strange beast. If you accept that the essential mission of a four-seat convertible is to cruise around and look good in the sun, then the presence of a 500-hp V-10 and an SMG transmission comes off as a tad incongruous, like a beach chair with machine guns. More so than the Jag and the Porsche, this is a car for the status conscious because it simply can't be topped by anything with a spinning-propeller badge. This fall, Porsche will bring out a new 911 Turbo convertible that supersedes the Carrera S, and Jag owners will be reminded of their penury by the occasional Aston Martin, but for BMW, the M6 convertible is the top dog. And that's important when you're charging $115,000 for a car that's less than a second faster to 60 mph--4.6 versus 5.4 seconds--than an E46-series M3 convertible.