"Everybody I know who's put a wheel off here has rolled."

So says senior editor Jason Cammisa of the tarmac snake running up Mount Tamalpais, near San Francisco. The pavement is damp, the gradient steep. Sod and twigs and leaves muddle the narrow pass. Through this morning fog, you could mistake Northern California for North Wales. Or Dagobah. It's not the kind of place you'd want to tempt with a fast, corn-fed, rear-wheel-drive sedan.

We've brought two.

Parked at a gravel turnoff is the 2015 Chevrolet SS, now available with a six-speed manual transmission and outfitted accordingly. Next to it is a 2003 BMW M5, near mint and Chiaretto Red over caramel leather. Arthurian relics are more easily obtained than this color combination. I'm content giving Cammisa first crack at the M5 and hairy two-lane while I hang back. When the big four-door reappears, his face is split wide, all teeth and dimples.

"It's magnificent," he says, "probably the best car BMW has ever built."

This from a man who's owned enough vintage Bavarian metal to fill a small continent. Cammisa suggests we make for California State Route 1, down Tamalpais and toward the Pacific coastline, in hopes of escaping the fog. Still giddy, he hands over the M5's toothy, old-school key. My turn.

Dean Smith

It's been a while since I've sat inside a Ferrari 575M Maranello, but I'm convinced the M5's cockpit is every bit as sumptuous. Pedal placement and dash layout are ideal, and good luck finding a four-door sedan with a better seating position. Once we begin our descent, though, it only takes three rapid, off-camber switchbacks before the M5's warts start showing.

The noise is somewhere between Days of Thunder and the end of days.

Steering feel was never this car's forte, and the recirculating-ball setup hasn't aged well. The gearbox is notchy. There's a wall of low-speed understeer. Traction control lights up at the first sniff of wheelspin. Frustrated, I drop back from Cammisa, far behind the Chevy's taillights, switch off stability control, and give the sport button a poke.

A moment of honesty: The M5 we borrowed is privately owned, and the tires were nearing rigor mortis. As a result, I only went nuclear for seven or eight miles. It was enough.

In the sharpest setting with electro-overrides off, the limited-slip diff is freed up to work its magic. Trees whip past. The road opens. With speed, the M5 sorts itself out. The tall, short-throw gear lever begins to cooperate, the suspension puts in work managing mass, and the chassis is left to strut its stuff. And by "strut its stuff," I mean "infect every fiber of your being with want," because it still feels so balanced 12 years on. Throttle response? Near preemptive. Nothing is this crisp or smooth, like all eight cylinders operate in some beautiful alternate universe where flywheels are weightless and friction isn't a thing. The V8's note isn't even loud, just a pure, growling churn, compounding over and over until 7000 rpm. Forget high-revving tens. Forget boosted sixes. This is what you're after.

Dean Smith

But it's not just the engine or the diff or the chassis, it's the cohesiveness of the sum, how the M5 gets you into a trancelike, syncopated rhythm of trail braking and heel-toe changes and tidy corner-exit oversteer. In a rear-drive car on a winding road, isn't that what we all want? I share these thoughts with Cammisa as we stop for photos, and he nods emphatically. "With the exception of the old navigation system, this M5 could go into production today, and it would blow everyone's mind."

He's right. And so I'm left staring at the Chevrolet SS, hoping it's brought some serious artillery to this fight. Because that M5, idling confidently and hungry for another go at the mountain, has a damn war chest at its disposal.

Why have we brought these cars together, and what makes them so special? Understand that the E39 M5, produced between 1998 and 2003, comes from a high-water period for BMW road cars. During that era, the Bavarians were turning out a specific flavor of automobile: outwardly, status symbols with mass-market appeal; at heart, driver-focused and dynamically impeccable. The E39 is that ideology incarnate, sleeker, meaner, and more capable than any sport sedan prior. So when the folks at BMW M tuned one, they didn't just throw down the fast-four-door gauntlet. They spiked it through the earth's core and out the other side.

Of course, there was plenty of hoopla over the engine. The M5's calling card had long been a megapotent, 24-valve straight-six, derived from BMW's homologation-special M1, that scared the living sauerkraut out of 911 drivers on the autobahn. For the E39, said six was replaced by a mighty quad-cam V8, at the time the most advanced roadgoing example of its kind. The 4.9-liter used independent variable valve timing for each of the four camshafts (a feature also found in the McLaren F1's V12) and an electromagnetic, lateral-g-force-activated, semidry-sump oiling system involving no fewer than three pumps. Subsequent output, a tidy 394 hp, matched that of the Ferrari 360 Modena. The enthusiast media soiled its collective Unterhose.

The enthusiast media soiled its collective Unterhose.

Yet for all that voodoo between its fenders, the E39 M5 is a fundamentally simple creature. Its brilliance boils down to an engine (eight cylinders, non-turbo), bolted to a transmission (manual), running back to the rear wheels, delivered in sensible packaging (four-door sedan). It's a shame the next M5, a self-shifting V10 monstrosity, burned the blueprint so spectacularly when it arrived in the U.S. in 2005.

Dean Smith

Robert A. Lutz, however, knows an archetype when he sees one. Before he became an R&T columnist, he was charged with righting the ship at Pontiac. The GM exec, a.k.a. "Maximum Bob," ordered up the screwball Pontiac G8 GXP, which paired a Corvette engine and gearbox with suspension geometry and dimensions eerily reminiscent of a 5 Series. These similarities were not coincidental. The G8 was a rebadged Australian-market Holden Commodore, developed entirely in Melbourne, where GM directed its top rear-drive engineers to evaluate the car against BMW sedans. Also along for the ride were a handful of eggheads who had helped develop the E39, as well as Holden's chassis tuner, Peter Hanenberger, a man known for benchmarking the Commodore against—you guessed it—an equivalent 5 Series. Alas, the GXP hit dealerships just months before Pontiac bit the bullet in 2009. And we were once again starved of a sport sedan made in the E39 M5's image.

Until the Chevrolet SS showed up.

Like the G8 before it, the SS borrows its Zeta chassis architecture from the Commodore, sized between the current Camaro and Chevy's Caprice police cruiser. Stashed under the hood is a 6.2-liter LS3 V8, producing 415 hp and 415 lb-ft of torque. Curb weight is 3935 pounds, and a clutch-type limited-slip differential is standard.

For 2015, the SS swaps nonadjustable shocks for Magnetic Ride Control (see: magnetorheological suspension, like that in the Corvette Stingray Z51). GM's close-ratio Tremec six-speed manual transmission, complete with a 3.70:1 axle ratio, becomes a no-cost option. (As in, you pay no monies and receive a manual gearbox. The best things in life, right?) Of course, you can still spec last year's six-speed paddle-shift automatic and taller 3.27:1 final drive, but you'd be missing the point entirely. Because the Chevy SS is now the only three-pedal, rear-drive sedan with room for five and enough naturally aspirated V8 grunt to give every passenger a hernia. Which raises the question: Could this be a rightful heir to the E39's throne?

The moment he hits the ignition button, Cammisa's impulse is to do a burnout. Mine, too. A massive burnout, something a SWAT team could use to disperse unruly protestors. We're all beasts of condition, big, slobbering Pavlovian dogs, and when the SS shimmies and snarls at start-up, it's ringing the Gen IV small-block bell.

"Everybody likes a bit of trashy," Cammisa admits.

Even so, he's having trouble warming up to the SS. It's like a raked 4x4 limousine next to the M5, and neither of us loves the Chevy's chrome body trinkets. But the broad, generic nose jibes with the sleeper-car motif, and the tail is all wide haunches and meaty 275-section rubber and cool duckbill trunk spoiler. Viewed dead-on at the rear from 10 paces, it looks the absolute business.

Dean Smith

Still, that means zilch once you're peering down the hood bulge and pounding on California blacktop. The seating position is higher than in the BMW, more upright, and the SS tramples the road instead of massaging it. Those new magnetorheological dampers? They might as well be filled with granite.

One plunge into the throttle, though, and the caroming suspension is forgiven: This 6.2-liter lump delivers on every sinful crate-engine-catalog fantasy you've ever had. The noise is somewhere between Days of Thunder and the end of days. Max engine speed is a thrashy 6600 rpm, but there's no use swinging the tach needle north of 5900. Torque is everywhere, always. The entire experience is a singular, blunt, pushrod onslaught broken only by hanging moments of clutch engagement.

"Everybody likes a bit of trashy," Cammisa admits.

And, God, are those moments sweet. The heavy pedal and solid, resonating driveline thunk of this six-speed fit the Chevy's personality perfectly. It makes you want to play around with the car, actually get down and drive instead of just vigorously aiming the thing. If you're intent on hooning, the SS will hammer around and make raucous sounds and powerslide out of hairpins. It'll do that every day, half-trying, for the rest of eternity, until cockroaches die off and Twinkies expire. You can do all the Camaro stuff, and Camaro stuff is neat. But when you're ready to ante up to do M5 work, the SS really hits its stride.

Bend after bend, nearing highway speed, we're approching the limit. The Chevy's much bigger than the BMW and just as controlled—when it comes to braking and steering accuracy, it's better. But you've got to be deliberate and trust the car. We pour into a succession of third-gear esses that'd send some well-honed coupes tank-slapping toward a ditch. Instead, the SS politely steps out, asks for a bit of steering and throttle, then gets in line and back to wasting asphalt. It's as capable and composed as hairy-chested four-doors get, two tons of blue-collar killer. Even Cammisa, who has serious reservations about the ride quality, has to offer props: "Brutally fast and fantastically American. Or Australian. Whatever. But, man, is this thing brilliant on a back road."

Dean Smith

The Chevy can't take the M5's crown, but not for a lack of thrills. Adjusting for inflation, the SS's sticker price is nearly half that of the M5's: In terms of overall build quality, a sub-$50,000 sedan today simply can't stand up to the flagship shrine of a great brand's greatest era. For everything the M5 offers in finesse, though, the SS answers in sheer cojones. Both are absolute dynamite.

The commonality here is a rounded competence, proof that cars can still feel elemental even through two tons of leather and electronics. Part of that is the healthy, all-motor V8. Part is the rear-drive layout and Q-car wrapper. The crux is a manual gearbox. Whether it's more impressive that BMW perfected this formula or that Chevrolet continues to deliver it in a time when nobody else will, I'm not sure.

To that point, the SS is only here because GM executive vice president Mark Reuss, a dyed-in-the-wool car guy, leveraged NASCAR marketing tie-ins to make it so. (His dad, Lloyd, a former head honcho at Buick, pulled a similar stunt delivering the Grand National GNX on the coattails of GM's turbo V6 Indy engine program.) Production numbers will be low, about 2500 annually, and when Holden disappears in a few years, the SS will likely die with it. BMW sold more than 20,000 examples of the E39 M5 worldwide. From volume play to niche dweller, 12 years represents an incredible paradigm shift. Also an alarming one.

People may not buy cars like this anymore, but they still seep into your soul. Drive one, and you'll know a fast sedan from a sedan that is fast. It's the difference between a manifest purpose and a latent function. And when the mountain road is foggy, out for blood, it's the difference between a snake charmer and a mouse.

This content is created and maintained by a third party, and imported onto this page to help users provide their email addresses. You may be able to find more information about this and similar content at piano.io