When you have two cars that are this similar and this nichey, there’s really no sense in covering every detail that we have already previewed in our BMW X6M First Drive. So we thought we would key in on what few differences there are between BMW’s more conventional X5M performance SUV (or SAV in BMW parlance, short for Sports Activity Vehicle) and the ballistic X6M crossover with its rakish, coupe inspired roofline (which BMW dubs a Sports Activity Coupe, or SAC – make of that what you will).

SAC vs SAV, long roof vs rakish profile, cargo space vs slightly less cargo space, which would win our theoretical Autos.ca dollars?

1a. How do you like your family vehicles?
A. I like a little flair and panache.
B. I don’t want too much attention on my vehicle’s looks so I can drive like a maniac.

1b. Do you prefer:
A. Minecraft and Lego?
B. Kim Kardashian and Frank Gehry architecture?

If you’re into bricks and blocks and practical square shapes, well, no question the long roof and upright design of the X5M will speak to your linear sensibilities. Our tester flies under the radar thanks to its muted Donington Grey (beige, really), so it’s definitely the option that will blend in at the school drop-off or mall parking lot. And perhaps fly under the radar of local constabulary.

The X6M, with its sloping hatchback roofline offers some instant drama and plenty of attention in Long Beach blue metallic, drawing more attention to the aggro body kit and chromed fender vents. I may be in the minority, but it seems a car of this power and capability deserves to draw attention rather than fade to the background like a wallflower at the junior prom.

2. But they’re essentially the same under the hood, right?
A. Yes.
B. Yes.

No getting around this one, both the X5M and X6M come packing the same big gun: a 4.4L twin-turbo V8 making 567 hp at 6,000 and above and 553 lb-ft torque between 2,200 and 5,000 rpm. BMW boasts that it is “the most powerful engine ever developed by BMW for an all-wheel-drive vehicle,” harnessing a pair of twin-scroll turbochargers, cross-bank exhaust manifolds, Valvetronic variable valve timing and direct injection. Despite weights of 2,386 kg for the X5M and 2,352 kg for the X6M, both launch to 100 km/h in 4.2 seconds in the sharpest Sport+ mode, or cruise in Eco Pro mode and burn through fuel like just a small private jet at 12.1 L/100 km on the highway and 16.6 L/100 km in the city.

I favoured pumping the extra gas and planting my foot to the firewall to see how the eight-speed transmission holds gears when under the gun, and the fortified AWD system distributing the torque to the four corners for blitzing away from lights and flicking the left paddle shifter in advance of corners and hearing the snarl of the downshifts as I searched for their limits and behaviour.

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