Driving pleasure doesn't get much more involving than this. The Porsche 911 alerts your sixth sense even in basic Carrera form, but you can, of course, upgrade according to your budget: Carrera S, Turbo, Turbo S, GT3, GT3 RS. Last in line is now the GT2 RS, which musters an awe-inspiring 620 hp. BMW tells a similar story, with the six-cylinder 3-series models meeting their master in the V-8-engined M3, which in turn is eclipsed by the brand-new 450-hp GTS. Both top-of-the-range coupes are track-oriented, featuring adjustable wings and suspension elements along with race seats and roll cages. On the road, they feel firm, look loud, and make a fair bit of noise, but if you don't mind extra tramlining and a harsh ride, these German sportsters are perfectly acceptable everyday stimulants from spring through autumn. Feel inclined to sign on the dotted line? Hold your breath. After all, the $245,000 Porsche is limited to 500 pieces, and BMW will assemble only 136 units of the fire-orange GTS, which costs about $140,000 in Europe and, unlike the Porsche, will not be sold in the United States.

Wednesday morning, Stuttgart-Zuffenhausen, Germany. The thermometer reads 82 degrees in the shade, and the one essential factory option our red 911 GT2 RS lacks is air-conditioning. "This car is for purists, and purists are used to suffering," comments chief vehicle line engineer August Achleitner, grinning broadly. I may be a purist, but by midday I'm sweating like a pig -- needlessly, because my broad six-foot, eight-inch frame carries enough surplus calories to outweigh four or five A/C units. Never mind. In this lofty pseudo-competition segment, every pound counts.

That's why Porsche will supply the GT2 RS on request with featherweight half-blind halogen headlamps instead of the much brighter bixenons. For the price of a vacation in Mauritius, you can also have a banzai lithium-ion starter battery and a pair of carbon-fiber front fenders, which together shave some 33 pounds off the total tally. All in all, Porsche engineers took more than 150 pounds out of the car that now sports plenty of dark-gray carbon-fiber body panels, spoiler lips, skirts, air intakes, and trim. There's no doubt about it: this is a very special-purpose vehicle conceived to outperform all previous 911s, including the 959 and the legendary GT1. While marveling at the tailor-made piece of ascetic engineering, though, I do wonder whether I am good enough to make full use of all these go-faster mods.

The temples throb and the discs rattle as too much man tries to bond with too little seat. Squeezing my bum into the one-size-fits-others carbon-fiber bucket adopted from the Carrera GT's is difficult enough, but fastening the seatbelt is downright painful. The driver environment is, shall we say, minimalistic. Climate controls are as basic as it gets, the inner door handles are made of red fabric loops, most cladding consists of carbon fiber, the radio slot is a gaping black hole, and the buttonless suede steering wheel sports a yellow straight-ahead marker at twelve o'clock. Right behind the torture-chamber Recaros spreads the spiderweb roll cage. The token carpets are mouse-fur thin, and the three polycarbonate rear windows distort like a large gin and tonic. While previous top-of-the-fear-ladder 911s used to be dressed in coal-mine superblack, our GT2 RS features an almost gaudy red-over-charcoal interior with contrasting Alcantara trim, real power windows, and a wafer-thin roof.

Let's get going. I turn the key above my left knee, feel that tiny flywheel kick the crankshaft into action, hear the intake snorkels cough then clear their throats, watch the needle of the rev counter tremble in anticipation, lean back and take a deep breath to fight that thump-thump in my palms, legs, and heart. Can we be friends, this Porsche and I? The clutch certainly suggests so. It is quite manageable, responds progressively, and bites with determination instead of overt aggression. The manual transmission is the same we know from the GT3. Stirring the shifter feels a bit like reaching into a sack full of antlers, but once you've got the hang of it, gearchanges are firm and positive. The effort, however, is high enough to provoke an attack of gout, and the throws are long enough to make you wish for an arm extension. Reverse requires a deep dive and then a positive push forward to the left or you'll clash with the first-gear neighbor who lives next door. Surely, the next-generation 911 GTs will benefit from the much more complete PDK dual-clutch box. Redlined at 6750 rpm, the twin-turbo flat six doesn't give you a lot of time to think about the perfect shift sequence. First gear hits the limiter before you can say "Wow!" and second is so short-legged that it will occasionally splay its cogs in protest against rushed downshifts. Sixth is a proper high-speed ratio that wrings out the engine on downhill autobahn slopes, where the red rocket will max out at an indicated 215 mph (Porsche claims a top speed of 205 mph). Where was the photographer to document this achievement? Exactly.

200-mph-plus may sound borderline insane for a rear-engine design originating in the mid-1950s, but this 911 boasts reassuring, newly found high-speed aerodynamic stability. The previous GT2 made me pale with fear above 175 mph, when the front end would pitch and waver and tramline and feel suddenly very light over bumps. That's now gone -- all of it. True, it took a rear wing that any condor would be proud of and a low-flying front splitter the shape of a giant black razor blade to fix these flaws, but the result is a 60 percent increase in overall downforce. The other major dynamic improvement concerns the substantially enhanced suspension compliance. Compliance in a GT2 RS? You bet. Ferrari reinvented compliance with the 430 Scuderia, and the rest of the gang followed suit. Porsche did so first with the new Turbo, and now the company has honed the chassis of the GT2, which feels to me even better poised than the almost equally extreme GT3 RS. Forget Sport mode -- it's suitable only for racetracks. But the Normal calibration of the adjustable PASM dampers, which was chosen to make the car shine on the Nurburgring, also works very well on highways and secondary roads.

The GT2 RS is marginally wider and lower than its predecessor. It also boasts a spicier PSM stability control setting; the tie rods, transverse arms, and spring strut lowers are attached to the body via zero-tolerance ball joints; a pair of so-called rear helper springs keep the main springs under tension even when the vehicle is momentarily airborne, which was thankfully not the case when I drove it.

Feeling and looking like a drenched wharf rat when the planet backed us into 93-degree humid heat well before noon, I had calmed down somewhat, because this obviously was no nasty beast as long as one drove it within the limits of adhesion. Which are high enough to eliminate 99 percent of competitors by simply outcornering and outaccelerating them. In the latest Swabian batmobile, 0 to 60 mph is an impressively swift 3.4-second affair. But to experience the real steamhammer effect, you need to leave the takeoff wheel spin behind you. After all, this hyperactive two-seater needs a mere 9.8 seconds to roar from naught to 125 mph, and a mere 20 seconds later you may tick the top-speed box. That's what 620 hp will do for you when it's installed in a car that weighs only 3020 pounds. This data might look invincible -- but the four-wheel-drive Turbo S nonetheless wins the sprint duel by 0.3 second, is only 9 mph less rapid overall, and costs a cool $85K less.

After half a day and many miles, the car and its driver have finally adjusted to each other. Lobster-faced and drinking water at a rate that almost matches the Porsche's thirst (about 14 mpg), I am now ready to find out whether the new GT2 is as unfriendly and unforgiving as its predecessor. Beating that model on the 'Ring by a full fourteen seconds should have been plenty of warning, but in an overly optimistic mood swing, I turned off stability control. Nah. I'll also deactivate traction control and see what happens. Let's check out whether these reflexes still work. The first run through a glassy-surfaced second-gear left-hander is spot-on. A bit of smoke, a nice slide, everything under control -- bingo. But the second run puts the alarm systems inside my brain on alert. The car understeers more emphatically, it takes a more determined effort to make the hot and grippy rear tires come unstuck, and the wide road suddenly narrows at the exit of the corner. You can guess the rest of the story: even more understeer, the slide commences even later, Monsieur Michelin's finest kiss the soft shoulder, and the car spins, which makes my heart rate go through the nonexistent sunroof.

What happened? When we stop for more water, I take a closer look at this 911's spec sheet. It reveals a maximum boost pressure of 23.2 psi, twice as much as Porsche quotes for the Turbo, along with 516 lb-ft of torque at 2250 rpm. Not to mention the 620 hp that the 3.6-liter engine dishes up at 6500 rpm. Compared with the Turbo and the previous GT2, the new model clearly needs higher revs to produce more oomph. As a result, it's an even sharper weapon, more black and white than a spectrum of grays, tuned for peak performance rather than friendliness. Second attempt, this time with a little more feeling. Stability control off; traction control on. An odd mixture -- almost every other manufacturer does it the other way around. Having said that, the setting generates a little more attitude, because it sedates the watchdog that oversees the transverse and diagonal forces. This time, I don't spin.

But this time, the car dictates the pace, the rhythm, the degree of extrovert attitude. This time, I physically feel the asymmetrical diff locking up to enhance grip and traction. This time, the chassis firms up in a semiactive manner, doing everything it can to keep the car on course. Although the tires squeal in protest, the fat and almost treadless 325/30YR-19 Pilot Sport Cup footwear in the rear sticks to the blacktop like maple syrup to your best tablecloth.

After a few haphazard tries, frustration sets in. Not so much about the sizzling, crackling, and now-parked 911 but about the obvious inadequacies of the man whose mission it is to master the monster. We spend the afternoon trying to find stretches of empty road, which ain't easy in the middle of the summer holiday period. On the autobahn, this car has no enemy but one's weaker self. Unlike the Mercedes-Benz SLS AMG, the Nissan GT-R, and the Chevrolet Corvette ZR1, which make high speed a relatively virtual zone you enter and leave without lowering or raising your visor, the GT2 RS is intense enough to create tension, noisy enough to phonetically distract, and demanding enough to constantly readjust the focus of your field of vision. As long as you keep your foot down, though, even 200 mph is unlikely to trigger instant cardiac arrest. But the mix of midcorner lift-off and ambitious g-forces remains as hair-raisingly eerie as it always has been in Porsche's rear-engine sports cars.

Once more, it takes time to reacquire the appropriate laissez-faire attitude. This car will sort itself out. It doesn't need an extrafirm grip, minute throttle-angle alterations, or constant corrections at the wheel. It can sort itself out. Bumps may dislocate your glasses, hydroplaning grooves may induce a roller-coaster wallop, and expansion joints may slice your flight path into disorderly pieces, but the car always sorts itself out. Until it starts to rain, until crosswinds enter the equation, or until the radius of a sixth-gear eight-tenths curve is a lot tighter than you remember it.

One can brake so late in the 911 GT2 RS that it's almost ridiculous. But of course you don't, because your passenger would jolt forward like a crash-test dummy and because public roads are poor playgrounds. This Porsche is fitted with six-piston front and four-piston rear calipers, with drilled and ventilated carbon-ceramic rotors and lightweight brake pads. To make the most of deceleration potential, the GT2 RS comes with extralarge heat-dissipation ducts in the front and with trumpet-shaped air intakes in the rear. When hot, the stopping apparatus shrieks like an old freight train, but that's a small price to pay for braking performance that calls for a replacement set of neck muscles by the end of the day. It's not just the fast-rewind negative acceleration that takes your breath away. It's also the urgency with which this Porsche squashes surplus energy that establishes real confidence, for the first time during this drive. Although it always helps to set the car straight before dropping the anchors, the computers have learned to cope very well with sudden changes like weight transfer, changes of direction, marginal adhesion, and split-friction surfaces. In the wet, it's a completely different ball game, because the Cup tires are very good at water-skiing but quite poor at carving.

One last time, we go out to explore our mutual limits. In more ways than one, the GT2 RS reminds me of the old Ferrari F40. Raw, extreme, basic, and yet very high-tech. In the F40, massive turbo lag followed by a mighty underhood explosion was what kept deflecting the line in heart-stopping fashion. In the GT2 RS, the flows of power are much more subtle. The two chargers work together, not in sequence. Throttle lag has been superseded by telepathic obedience. The torque curve is now shaped like a low, long plateau.

What does this mean to the captain at the helm? That he has even less time to respond, that the forces are even more brutal, that catch and release has turned from routine to a form of art. If you can find a reasonably smooth surface, a late sidestep followed by a brief correcting flick at the wheel is about as much drama as you want to induce. But those long slides that used to paint an unforgettable smile on one's face are much harder to ride out in this 911, which is always ready to bare its teeth. Although carefully massaging the throttle sounds like the easiest trick in the book, the ultrawide rear tires keep fighting the torque wave because their goal in life is to slice, not to slide.

I'm not sure if there exist enough rich Walter Rohrl-like bravados to fully relish the true potential of the ultimate rear-wheel-drive 911. Although I did approach the car with more respect than any other Porsche currently in production, my awe for the wild thing kept growing in the course of the day, and by evening, I handed back the key with a mix of relief and reluctance: Relief, because we have all the photos in the can and the car went back unscratched. Reluctance, because I could not pluck up enough courage, competence, and confidence to work this car through its paces and stay on top of the game at all times. It's not just the random snap oversteer that makes gray hair go white, it's also the almost forgotten counterswing that follows which proves that some skills don't age nearly as well as red wine. On a track, this is bound to be an almost invincible tool for the brave and gifted. On the autobahn, the GT2 RS has all the go one could ask for but not enough refinement so that one would be comfortable relaxing. On secondary roads, the most venomous 911 this side of the various Clubsport editions has got what it takes to throw down the gauntlet to any Ferrari, Lamborghini, or Bugatti. Except, perhaps, an adequately talented driver.

Now for the BMW M3 GTS
Sunday lunchtime, Ascari circuit near Malaga, Spain. Welcome back to a 93-degree summer day, but at least this time the heat is Death Valley-dry, and there's a stiff mistral blowing from the sea. BMW has chosen the Spanish location to celebrate twenty-five years of the M3, an event highlighted by the launch of the brand-new limited-edition GTS coupe. The demanding Ascari racetrack is a great mix of fast and not so fast, up and down, mirror-smooth and rippled. The quickest corner is good for about 135 mph, and the slowest kink is perfect for second-gear slides. There are two chicanes, a couple of third-gear bends sporting a challenging switch from positive to negative camber, three climbs and three according descents, a long start/finish straightaway, and a wide pit lane. I counted twenty-five bends, most of them left-handers. Although there are five generations of M3s to choose from here today, we quickly filter through to the brand-new GTS, which is painted fire orange -- the same color used by the long-defunct Jagermeister racing team that fielded all kinds of fast BMWs from the 2002 to the 3.2CSL. Predictably, five days were not enough to let my body recover from the Porsche 911 GT2 RS experience. The Recaros installed in the M3 GTS also looked like items out of a brochure for bondage aficionados, but they were thankfully a full size wider, more thoughtfully padded, and quite generously adjustable. Although both cars come with a six-point harness free of charge, inertia-reel belts are fitted for predominant road use. A/C and music cost extra in the BMW, and since chassis number 003 tested here will probably end up as an enthusiast's track day toy, cool air once again remained a pipe dream. Neither the GT2 RS nor the ultimate M3 need a radio. After all, what you hear is the best music in town, the goose-pimple-growing sound track of true hard-core street racers, beautiful mechanical noise, a luscious and loud concert of high-strung automobiles at work. First, we're due to run a couple warm-up laps behind an E46-chassis pace car. After that, the rarest, dearest, and fastest-ever M3 begs to be put to the real test.

With a tarmac temperature of well over 120 degrees, the slow-in, fast-out rule is absolutely critical to the BMW's cornering performance. Over-drive it, and the front tires will heat up in no time at all, first provoking terminal understeer and then shredding themselves to pieces in a smelly hara-kiri farewell. That's why a smooth sequence of motions is so important for the well being of both car and driver. Since we're not here to set a new lap record, I brake relatively early at the end of the two fast straights. And although turn-in can be quick and energetic, you don't want to fully load the car's front end until the change of direction is about two-thirds complete. It takes a while to learn and understand this track, to get the line right for the double-apex corners, to eliminate unnecessary gear changes, to settle on the best compromise through the chicanes, and to zoom in on the correct brake and turn-in points. After ten laps, I take a break to discuss the setup with chief project engineer Rolf Scheibner.

The gleaming citruswagen performs with aplomb, but I would be happier still with an even more neutral setup and with a slightly tauter front suspension for more stability in the wobbly esses. Scheibner gets in the car, drives three laps, returns to the pits, and adjusts the front tire pressure and the rear wing. "Now try again," he says. "I bet you will come back with a smile on your face."

The M3 content of the GTS version is a perceived 40 to 50 percent. True, the basic shape is familiar, but the add-ons are all-new, and the dark and barren cabin feels almost alien. There are no rear seats, the front buckets wear the Nurburgring seal of approval, the slim center console has been decontented, the steering wheel and the instruments are special to the GTS, and instead of the usual wood and leather mix, there's wall-to-wall carbon fiber with some Alcantara accents. The roll cage is painted body color, the black suede-rimmed steering-wheel rubs off like an ink pad, the rear side windows and the backlight wear plastic stickers, and the electronic damper button (EDC) has disappeared since there's no longer a comfort setting to select.

Again part of the parcel is the M Drive Mode (MDM) button, which speeds up the communication among throttle, engine, and gearbox while at the same time dialing in a more aggressive stability control calibration. With DSC off, the car reels in the entire electronic safety net, so you're on your own when the growling bigger-bore V-8 sets the fatter nineteen-inch rear tires afire.

We go back out, this time with MDM active and with the well-broken-in Pirelli tires gradually adopting a liquoricelike consistency. "They'll need replacing before the day runs out," says our friend from R&D, "so don't worry about wear and tear." I take that as an order. MDM is giving the car some leeway through the third-gear curves, but when disturbed by a sequence of vagaries in the surface, it interferes momentarily through two 125-mph-plus right-handers. Two laps later and charged with enough self-confidence to challenge the Klitschko brothers (in tennis), I remove the final filter and deactivate stability control. What a treat! The GTS is now totally at ease, and my mind-set begins to adjust accordingly, corner by corner and lap by lap. Absolute speed is almost immaterial in this getting-to-know-you process. What matters instead are concentration, accuracy, timing, and trust. No, I don't always get the line 100 percent right, I don't always brake perfectly and just in time, and I don't always manage to match revs and radii, speed and surface, approach and apex. But the M3 treats my occasional clumsiness with the nonchalance of Grandmaster Flash, shrugging off enthusiastic curb contacts, ironing out unintended line deflections, and soaking up overly optimistic dips and dives. This car doesn't punish you for making mistakes; instead, it takes you by the hand, leads you through, and shows the way, time after time.

Roughly twice as expensive as a normal M3, the Sunkist version is for obvious reasons not twice as agile or twice as fast. In lieu of the 4.0-liter V-8, the M GmbH division installed a high-revving 4.4-liter unit good for 450 hp at 8300 rpm, up from 420 hp. The maximum torque climbs from 295 lb-ft at 3900 rpm to 325 lb-ft at 3750 rpm. The acceleration from 0 to 62 mph now takes only 4.4 seconds instead of 4.6 ticks, and the maximum speed has increased from a governed 156 mph to an unrestricted 191 mph. True, the GTS is one very special M3 for the price of two, but it has much more to offer than a 0.2 second advantage against the stopwatch, such as a unique livery, a high-performance engine and transmission, an uprated chassis, a substantial 154-pound loss of body fat, clever ground-effect aerodynamics, stronger brakes, and the competition-car genes of the M3 GT2. Don't let the marginally quicker acceleration time fool you -- this is a totally transformed car, from the bespoilered bottom to the carbon-fiber top. Individually, the listed modifications may not justify the GTS suffix. As a whole, however, they turn this 3-series on steroids into a more addictive drug, a purer driving machine.

For Ascari, the M team lowered the ride height by 0.6 inch in the front and by 0.5 inch in the rear. In addition, they chose a specific fast-track setting for the shock absorbers and the wheel camber. Last but not least, they readjusted the front splitter and the rear wing. In total, implementing these changes took about fifteen minutes. I didn't drive the virginal car as it left the factory, but I did compare the Ascari special to the latest M3 with the competition package. Although the two models are quite close in character, the difference is like night and day when you put them through their paces on the circuit.

Whereas the GT branch of the 911 tree becomes more and more unforgiving the further away you climb from its Carrera roots, the top-end M3 is almost as accessible as a 335i with M suspension. No, this isn't due only to the admittedly lower limits and the less extreme velocities. What makes this BMW such an eye-opener are, above all, its even and good nature, the transparency and progressiveness, and the equilibrium between action and response. Exploring the limit is all about confidence -- the GTS provides just that, in rare abundance.

While early M3 generations celebrated power oversteer for the sake of unbridled hooliganism, the E46-chassis, the current E91-edition, and in particular the new GTS perform a much more professional and sophisticated fusion of stick and slide. Instead of being all over the place all the time, the roadholding of the GTS seems to be guided by an invisible induction loop, grip appears to be defined by a moving magnetic field, and directional stability has that unerring hypnotic touch. I must have spent about ten laps marveling at how the incredible performance can be intuitively tweaked by steering, throttle, and brakes. For the following ten laps, I was knocking on fate's door by running very wide through the second-gear U-shaped turns and a little wide over the softly curved curbs at the exits of faster corners. Then it was back to tightening and polishing the line, playing with camber changes and the variably grippy parts of the track, where cocky excess torque can be your impromptu ticket from drama to trauma. It always pays to remember that no runoff area is big enough to hide your broken ego ...

The M3 GTS is fitted with a stiffened suspension, matte-black Y-spoke rims shod with 255/35YR-19 Pirellis in front and 285/30YR-19 Cup tires in the back, an exhaust made of titanium, larger-diameter high-performance brakes, and a seven-speed dual-clutch transmission with whiplash action thanks to a momentary power boost during full-throttle upshifts. You can store your favorite setup via the MDM button, which no longer needs to be reprogrammed after the engine has been turned off. My preferred mix of adrenalin, testosterone, and Shell V-Power is the second-fastest shift speed, stability control off, and both windows halfway open for a sufficiently rich mixture of air and noise. Although a manual transmission is inherently more involving, the GTS's dual-clutch box is quantifiably slicker and quicker, period. It would be an even more functional tool if the paddles were attached to the steering column and not to the wheel itself. Although the throttle response is about as greedy as a piranha that smells blood, the shift action is still smooth enough to pardon even emergency midcorner downshifts.

Solid chassis and suspension control is essential for a car like this, and so are reassuring brakes and haptic steering. The M3 GTS does without the usual compound rotors. Although this solution may appear low-tech these days, the mix of cast-iron discs and aluminum pads connected via steel pins is just as powerful and progressive. Easy to modulate and relatively effortless, the system blends strong initial bite with plenty of staying power. But the plum in this Bavarian fruit cocktail is once again the hydraulic rack-and-pinion steering, which easily outshines those of its electrically operated counterparts. Quite meaty around the straight-ahead position, the direction-finder is sharp and quick, accurate and responsive, always connected, rarely underdamped, and never ever ambiguous. Holding a slide with the fat-rimmed wheel and supporting that vital right-foot-and-both-arms intralink is a special talent of this remarkable BMW.

There might never be a week like this again: Porsche 911 GT2 RS, BMW Megacity Vehicle, Bentley Continental GTC Supersports, Mercedes-Benz CL, BMW M3 GTS. It's funny, though, that cream-of-the-crop does not always equal most desirable. I would, for instance, rather own a sublime GTC Speed than the shrill Supersports, and I prefer the practical S-class to the pricey CL coupe. The 911 is obviously a much more complex issue. Personally, I find it very hard to argue against the Turbo S. It is incredibly quick, astonishingly sure-footed, and certainly no instrument of torture. The 911 GT2 RS, too, is much more compliant and forgiving than expected. It's only when you overstep the fence to feed the lion that the animal is liable to bite back. And when it does, 620 hp and 516 lb-ft can do more damage than the 450 hp and 317 lb-ft of the even more aggressive GT3 RS. What the GT2 deserves is a professional tamer, a driver who can handle wild animals, a pro who's not afraid to keep working on his handicap. You guessed it: that's not me. The only feline I occasionally come to terms with is Minka, our eight-year-old Siamese cat.

The bloodline of the M3 thins relatively quickly as you venture down the ladder to the four- and six-cylinder 3-series specimens. Although the 335i tops the value-for-money chart ahead of the supertorquey 335d, the M3 is still special in the way it focuses on fluency and feedback, intuitive handling and extrovert performance, grand gestures and concise control. The GTS is all that and more. More involving, more radical, more fun, more competent, as well as considerably faster, hotter, and leaner. If you can live with the humorless suspension settings and the antisocial noise levels, this BMW might even work as three-seasons car, but only with A/C and rather not in DayGlo orange. The GTS is expensive for an M3 but a bargain vis-à-vis the GT2 RS. It is also accessible in a less breakneck way, its limits are manageable enough to be enjoyed on select stretches of public road, and its appeal is less elitist but by no means proletarian.

Sadly, waxing lyrical won't help acquire either of these objects of desire. They're both sold out, so you may want to wait for next year's all-new 911 or for the fifth-generation M3, which is due in 2012.

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