2012 Mercedes-Benz E63 AMG(Photo: Justin Couture)

We did our best with the time we had, strafing some of our favourite back-roads on and around the Niagara Escarpment, all in the pursuit of automotive truth. And some did emerge.

The E63 emerges as everybody's friend, but nobody's One True Love. It drives slowly really well: smooth shifting, seamless idle-stop, linear power delivery, light steering. Apart from a driving position that at least one of us found too low, the AMG's forte is its user-friendliness: "this car feels like it was designed to bowl over a novice driver," noted features and road-test editor Couture.

Driven in attack mode the E can perform heroically, but its abilities won't overwhelm you. Then again, neither do they fully engage you. Its most extreme settings still aren't that extreme. The steering, especially, is a tad lazy on-centre. This is still a Mercedes, after all, and at the end of the day, a Mercedes should never challenge or un-nerve its driver. (Perhaps we shouldn't be too surprised: an AMG rep once told us that a surprising number of its customers are not hard-core performance enthusiasts: they choose the AMG simply because it's the most expensive version ...)

2012 BMW M5 interior(Photo: Justin Couture)

The M5 doesn't do slow quite as well as the E63. Some surge in the clutch take-up at launch, and slight turbo lag, conspire against seamless stop-and-go driving. Good or bad, the chassis reports back every nuance of the road surface. Ride motions sometimes set you bobbing on the springy seat.

The M5 is for those who understand its ultimate capabilities and have both the will and the skill to use them. Push all the right buttons, use the paddle shifters, and the M5 becomes an intensely focused driving machine. It rides hard, revs ferociously, hangs its tail out, and upshifts with the shocking suddenness of a rifle-shot. Perhaps most contentiously, the steering effort becomes really, really manly. At times it seems you have to wrestle it into sharp turns.

We weren't unanimous about the M5. Its size, mass and hefty steering "give it an almost stern, robotic feel," was one log-book comment. Then again, "I love the fact that it's so deeply and truly unhinged when you set all settings to Sport+," said another.

2012 Porsche Panamera Turbo S interior(Photo: Justin Couture)

While the M5 and E63 are maxxed out versions of mainstream luxury cars, the Panamera was engineered from the start as an Alpha-dog performance sedan. Yet it can do luxury with surprising conviction. Its engine is several shades quieter than the others', and is even more relaxed on the highway (1,700 rpm at 120 km/h!). There may be only two back seats, but they cosset their occupants. In Comfort mode the air suspension rides softly — almost to the point of land-yacht floatiness, at times. The opulence of its (optional) cognac/cedar furnishings makes the other interiors seem austere.

Other virtues are equally valuable for both sedate and sporty driving. You can tailor a low-slung sports-car driving position within a narrow cockpit that shrinks the car around you, or you can set the seat high for great sightlines that are as conducive to precision parking as to picking the perfect path along winding pavement. All-wheel drive promises all-weather security as much as it lets you deploy every one of the 550 horses to devastating effect on dry pavement.

2012 Porsche Panamera Turbo S and Mercedes-Benz E63 AMG(Photo: Justin Couture)

Same story with the steering. It's light enough to please even the most disinterested driver, while lateral-g addicts will delight in its clean, frictionless on-centre precision. Somehow the Porsche contrives to be the most stable of the three and the most agile: it's the largest and the equal-heaviest, yet steers and turns with the nimbleness of a car half its size.

It's also twice the price of the others. For most of us, that doesn't matter because we can't afford any of them. For a fortunate few, it doesn't matter because they can afford any of them. To the latter we say: buy the Porsche, and be thankful that you can.

And then there are those who can afford to spend $100K but not $200K. To them we say, buy the M5 if you relish the challenge, or the E63 if you'd prefer a car that's a little easier to get along with in the daily grind. Whichever you choose, don't expect us to feel sorry for you.