ArcaMax

Some of the quickest cars on the road aren't even cars - much less high-performance sports cars. This BMW X5 M, for instance. Don't let the four doors fool you. Let them fool the dude sitting next to you at the light in his 911.

With not-far-from 600 hp under its hood, the gag is on pretty much everyone - in anything - who thinks they can outrun this thing. Because few are the contenders - two doors or four - capable of breaking into the high threes, zero to 60. Which is what you'd need to beat the X5 M.

Which excludes the Porsche 911 Carrera. The Cayenne Turbo, too. And the new Range Rover SVR. The Benz ML63 AMG? Easy meat.

WHAT IT IS

The X5 M is - forget the preliminaries - the strongest, quickest, baddest crossover SUV on the road. Under - or over - $100k. It outruns all its rivals, the Porsche Cayenne Turbo, the Range Rover Sport SVR and the AMG-amped Benz ML.

It's also quicker (and not by a little bit) than a 911 Carrera coupe. And the 911 hasn't got room in back for a wet labrador retriever. Nor can it cart around five people - or deal with snow. The X5 can do all that.

What can't it do? Go more than about 200 miles on a tankful. Ah well. You can't have everything. Base price is $98,700. By no means cheap thrills. But cheaper - and more thrilling - than the Cayenne Turbo ($113,600) and the Range Rover Sport SVR ($110,475).

The Benz ML63 AMG's base price of $98,400 is a few hundred bucks lower than the BMW's. But then, so is the Mercedes' performance. Look in vain for quicker - much less four-doored - alternatives. Better yet, go out and look for victims.

WHAT'S NEW

The X5 M is the latest M-tweaked BMW - "M" being BMW-speak for sehr schnell(that's really, really fast). In addition to another 100-plus horsepower vs. the non-M X5 xDrive50i - the X5 M receives the usual ensemble of complementary M upgrades, including high-performance (and driver-adjustable) calibrations for the eight-speed automatic and full-time xDrive all-wheel-drive system, much more sporting suspension settings , flying saucer-sized (and cross-drilled) brake rotors and massive powder-coated calipers peeking out from behind M-specific 21 inch light-alloy rims just barely skinned with ultra-ultra low-profile "summer" tires.

Plus true dual exhaust ending in quad splitters out back, an M-specific gauge cluster with a 200 MPH speedo (you'll need it) and subtle tweaks to the bodywork such as functional front fender air vents to put some visual distance between it and run-of-the-mill X5s.

WHAT'S GOOD

911 acceleration - with foor doors and room for five. Costs $10-$13k less than not-as-quick Porsche Cayenne Turbo and Range Rover Sport SVR. Discreet like an Ashley Madison hook-up. No one needs to know.

WHAT'S NOT SO GOOD

Hasn't got the Cayenne's ability to turn heads. Not as potentially off-road-adroit as the Range Rover, which offers more ground clearance, 4WD Low range gearing and a higher tow rating (6,600 vs. 6,000 pounds.) Tighter back seats (and less cargo capacity) than the Benz ML63 AMG. Frequent stops for fill -'em ups.

UNDER THE HOOD

There may indeed be a replacement for displacement. Despite having the smallest V8 of the bunch - 4.4 liters vs. the ML63 AMG's hunky 5.5 liter, the Range Rover' SVR's 5.0 and the Porsche Cayenne Turbo's 4.8 - the X5 M's is the strongest: 567 hp (and 553 ft.-lbs. of torque) vs. a somewhat puny 518 (and 516 ft.-lbs.) for the Mercedes, the RR's 550 (and 502 ft.-lbs.) and 520 (and 553 ft.-lbs.) for the turbo Porsche.

The BMW is - not surprisingly - the quickest, too. Zero to 60 in four seconds flat - vs. the second-place Cayenne (4.2 seconds), third place Range Rover (4.4 seconds) and - way back there in fourth - the almost slow-pokey 4.8 second to 60 Mercedes ML63 AMG.

Benz does offer a little blue pill in the form of an optional $6,550 AMG Performance Package (on top of all the AMG stuff you already bought) that tightens up the race, increasing the 5.5 V8's output to 550 hp and 560 ft.-lbs. of torque - but even with the additional AMG Viagra, the Benz's acceleration (4.5 seconds to 60) still doesn't quite match the BMW's.

It must be reiterated that the X5 delivers these goods for many thousands of dollars less than all three of its rivals. BMW is not usually the, uh, "value" choice. But in this case, you get really do get more for less.

An eight speed automatic is standard (the Cayenne and Range Rover also have eight-speeds; the Benz comes with a seven speed) as is a full-time all-wheel-drive system. The X5's - like the systems you'll find in the others - is there chiefly to modulate the power, which would otherwise be Too Much for the general public to deal with. Think about it. A 1970 Hemi 'Cuda - one of the brutal original-era muscle cars - was sporting a mere 426 hp. The X5 M has nearly 150 more hp than the legendary Street Hemi. You do not put that kind of power down using just two wheels.

Michelin would have to keep the tire factory running double shifts to keep up with the demand for fresh Pilots - and the insurance mafia would stroke out. There would be congressional hearings, probably - and what about the children? AWD is a way to keep a lid on things.

It helps keep these berserkers accelerating in a straight line rather than sideways. The original muscle car era was kiboshed in part because of the perceived run-amokness of rear-wheel-drive performance cars with maybe 350-400 or so honesthp under the hood. With AWD - and wrapped up in crossover SUV camouflage, BMW, et al, can get away with selling 500-plus hp rides and (so far) no squeals of outrage about "safety" from the usual quarter. Plus it actually is safer.

That much power funneled through just two wheels (those wheels shod with "summer" ultra-performance tires) would be a disaster on anything but the driest of roads. In snow, you'd be as helpless as Ned Beatty by the side of the river on that ill-fated canoe trip.

The X5's AWD/eight-speed automatic has (like the others) driver-programmable settings that can be tailored to suit your mood - from Comfort to Sport Plus. In addition to the transmission/AWD and suspension settings, you can also tailor steering feel and chassis damping to suit. Noteworthily, you can adjust these parameters individually and independently. So, for instance, you can leave the steering effort in Normal (a bit more assisted than it would be in Sport) with Sport Plus mode engaged for the drivetrain. Like memory seats, you can also program the settings you prefer into the system and engage them with the touch of a single button as opposed to having to punch up the settings you want each time you go for a drive - after your wife has gone for a drive.

ON THE ROAD

The four minute mile is considered pretty much the extreme limit of human performance. The performance of cars seems to be nowhere close to the limit. They keep on getting stronger and stronger. Faster and faster. Here we have a 5,200 pound SUV that will run mid-high12 second quarter miles all day long (or as long as the tires and gas last) while idling as smoothly as a Bill Cosby denial - without overheating, either.

While carrying five people - with the AC humming and the tunes playing through the 16 speaker Bang & Olufsen ultra-premium audio rig.

It barks a little through the free-flowing dual exhaust and quad tips when you first fire it up - like the better-pay-attention-to-it guttural growl of a semi-sleeping Rottweiler. But otherwise, it's a pussycat. Until you want battlecat.

There is so much torque - more than 500 ft.-lbs. of it available when the engine's idling - that the X5 M is actually easier and more comfortable to drive in stop-and-go traffic than most economy cars. Because the least touch of the accelerator results in near-teleportation. Supposedly, Elvis wore that cape on stage because it made him feel like a superhero - which helped him overcome stage fright. The X5 M will make you feel like a superhero, too. The moment you first give it full pedal, you will know the feeling of stepping into that phone booth and ripping off your Clark Kent sunglasses.

Some perspective: The X5 M's engine produces about 70-75 percent of the output of a current Nextel Cup stocker's all-out race V8 - but without the race car's shake/rattle n' roll. It'll hit almost 190 MPH on top. Which is about 75 percent of the top-end of a Nextel Cup car geared for the Daytona 500.

But unlike a Nextel Cup stocker, the X5 M is street legal, emissions-compliant and will definitely last longer than a 200 mile race (though maybe it won't make it 200 miles on a single tank; read on).

Even more jaw-drop-worthy, it corners. The sensation of being that high up - while going this fast through an apex - is a sensation your body and mind will initially have trouble reconciling. Like a too-good-looking blind date, you wonder - What's the catch? When is the other shoe is going to drop? It never does.

Some more perspective: A Porsche 911 is just 51.3 inches high at the roofline and has about 5.5 inches of ground clearance. The X5 M stands 67.6 inches high and its skirts are 8.1 inches off the pavement.

Yet the X5 can trace a 911-esque line through the esses. It is like watching a five-foot-five guy score 20 points in an NBA championship.

The Cayenne Turbo is comparably adroit in the curves - but can't keep up with the M in a straight up drag race. Plus it costs more. A lot more.

The Benz ML63 and Range Rover Sport, meanwhile, are much more "trucky" than either the M or the Cayenne - both featuring more in the way off-road capability (including Low range gearing and more ground clearance). But this inevitably compromises what they're capable of laterally, on road. They both have higher-than-you'd expect capabilities in that respect. But neither of them feel remotely 911-esque. The X5 M does.

AT THE CURB

The X5 is the biggest of the four, but a bit less space efficient than some of its rivals. The BMW's back seats, for instance, have less legroom (36.6 inches) than in the Benz (38.4inches ) despite the X5 M's being 3.6 inches longer overall (192.7 inches vs. 189.1 for the ML63 AMG).

On the other hand, the BMW has significantly more cargo capacity (76.7 cubic feet in total) than either the Cayenne (62.2 cubic feet) or the Range Rover Sport (62.9 cubic feet) and only a little bit less than the ML63 AMG (80.3 cubes) and is the only one of the four with a standard two-piece tailgate. The lower section folds out and down while the upper section opens - conventionally - up. When the lower section is folded down, you get what amounts to a bed extender - about a foot more load floor. This is handy whether to sit on during a tailgate party or for hauling stuff home. With the lower section locked in the up position - and the upper section open - you have a handy little dam to keep cargo in the X5 that might tend to slide out if not tied down adequately in other SUVs.

Car People can spot the M version of the X5 at a glance. It is the only X5 with four exhaust tips, a pair of front fender air extractors (functional, not cosmetic) and subtle wheelwell extenders (necessary to keep the 21 inch wheels/tires scooched within the bodywork). But to most people, it's just another - yawn - crossover SUV. A clearly expensive one, without doubt. But few among the uninitiated are remotely conscious of the 911-thrashing capabilities discreetly tucked within that unassuming shell. This is a beautiful thing - because it makes it much more feasible to thrash 911s. Or rather to drive regularly on public roads as if you were in a 911… and get away with it.

Out in the wild, effective predators are ambush predators. They make use of camouflage. You do not see them coming ... until you feel the fangs sinking deep into the back of your neck. And by then of course it is much too late to do anything about it. You are doomed.

The X5 M fits that bill. The 911 - magnificent though it may be - does not.

Neither does the Cayenne Turbo, for that matter. Because it looks like a 911 fattened up. The Porsche profile is unmistakable and when another driver sees thatface in the rearview, he knows what to expect - and that puts you at a disadvantage, even against much lesser machinery. That Prius up ahead? He can simply block you in, out of spite. Then, all the horsepower in the world is as useful as a thong at the Vatican.

It's a never-ending treat to drive the X5 in heavy traffic - to thread the needle in heavy traffic - which you can do much more easily, with near-impunity, not just because of all that power but also because you can use all that power. They almost never see you coming. Same goes for The Law.

THE REST

The M gets a different shifter than regular X5s. It's a little stubby toggle thing that's fully drive-by-wire and so lacks tactile feedback. It's functionally faultless but something more mechanically engaging would be more appropriate here, probably.

On the other hand, the M's exhaust system - which features a pressure release system under wide-open-throttle - makes up for that. It's similar to the set-up that's available optionally in the AMG-tuned version of the Benz GLA (reviewed here). It works like the old-school exhaust cut-outs that muscle cars back in the late '60s sometimes had - but it's fully automated. No need to pull a cable to bypass the mufflers. Under WOT, pressure is released via vacuum-actuated flapper doors - accompanied by a sound that rips the air like a mini sonic boom. This happens at the crescendo of each WOT upshift, so as many as eight times in sequence. Your neighbors will feel like the sky boss in Top Gun when Maverick's Tomcat did an unauthorized flyby, both afterburners lit. There goes the coffee...

The M's traction/stability control also has more libertine programming. While straight-line burnouts are not allowed, you can smoke 'em sideways a bit, if you like.

Gas mileage is about as relevant a consideration here as the fertility of nursing home residents. When you are interested in 500-plus hp twice-turbo'd V8s and top speeds approaching 200 MPH you are not, by definition, much interested in how much it costs to feed it.

However, you might be interested in how often you'll need to feed it. Even with a pretty large (22.4 gallon) fuel tank, the X5 M can drain it dry in 200 miles. Less, if you're really working at it. EPA rates the BMW as being capable of 14 city, 19 highway (vs. 14/21 for the Cayenne Turbo, 13/17 for the ML63 AMG and 17/23 for the "class best" RR Sport SVR) which maybe it is. If that's what you're trying for.

But isn't that like trying to keep an ice cream cone from melting as opposed to just eating the thing? EP (me) rates it at about 8 MPG. A larger tank would be great.

THE BOTTOM LINE

I'm always looking for a way to end-run the system, to get away with everything they're trying to shut down and suck the life out of. The X5 M is like one of those horse needle things they use to revive someone technically dead with a shot of epinephrine straight into the heart. If you haven't got a pulse, this will restore it. If you want to feel alive again, this will do it.

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www.ericpetersautos.com or EPeters952@aol.com for comments.