Mighty German brothers

* BMW E60 M5 , 5.0-litre, 507 bhp, seven-speed SMG

* BMW E60 M6 , 5.0-litre, 507 bhp, seven-speed SMG

Bmw M5 & Bmw M6

Stuttgart, Germany — Comparing the BMW M5 with its coupe brother — the M6 — is like arguing over who's hotter: Jennifer Garner or Jessica Biel. What's the point? Any self-respecting guy would be happy with either. Same goes for the M5 and M6. But off to Germany we went, to answer this simple question: If you had to choose (the M5 or M6, not Garner or Biel), which would it be? The M5 and M6 have many similarities, but the one thing that's identical is the drivetrain. And BMW's almighty, all-conquering 5.0-liter 90-degree V-10 is simply magical. This is a supremely advanced powerplant that uses individual throttle valves for each cylinder tied to an electronically controlled throttle-by-wire system; response is immediate. BMW's variable double-VANOS camshaft management continuously varies the valve timing to create better high-rpm power and a very consistent torque curve.

Result is one of the most free-revving engines ever, along with an insanely potent 500 bhp at 7750 rpm and 383 lb.-ft. of torque at 6100. Fire either one of these V-10s up and they sound…like complete rubbish, at least at idle; think of the uninspiring, industrial-sounding hum modern turbodiesels make.It plays such a rippingly beautiful song up to its 8250-rpm redline that you find yourself running up and down through the gears just to hear it one more time.

All this power is harnessed to a 7-speed sequential M gearbox (SMG) operated either by steering-wheel paddles, a center console lever or you can just leave the system in full automatic. This third-generation SMG is far superior to any before, providing jerk-free (computer-controlled) clutch slips as you pull away from a stop. This is the only transmission available for the M5, though a true manual (that's right, with three pedals!) is said to be in the works for the M6. Incredibly quick (though abrupt) full-throttle shifts in the Drivelogic's sportiest setting (of 11 to choose from) mean both the M5 and M6 chirp the rear tires going into 3rd gear.

While this system (like Ferrari's F1 gearbox) is completely state-of-the-art, you do lose the driving pleasure associated with old-school techniques such as heel-and-toe downshifting. Personally, I'd also prefer the paddles to be steering-column mounted instead of wheel-mounted; as someone who shuffle-steers, it can get confusing as to where the proper paddle is.

Which one would you choose ...