BMW's X6 M and X5 M: the power and the glory

Monday, 4 May 2015

They don't even sound like V8s when they're driven on part-throttle.

But as their between-the-vee twin-scrolled twin turbos chime in at full bore, all the hammers of hell seem to be let loose and the whole plot reaches for the horizon with incredible haste, accompanied by that unmistakeable rumbling beat as more than 500 horsepower is brought into play.

Then you know they're V8s, nothing else sounds like one, especially when they're running to beyond 6000rpm, as they do in these fellers.

The slope-roofed coupe-like X6 M might not look it, but it's marginally longer than the more spacious X5 M. Photo: Mark Bean/Fairfax NZ

BMW has worked hard on its second iteration of X-drive vehicles with M for motorsport suffixes; the X5 M and the X6 M, adding 15kW and 70Nm to their powerunits, which now put out a thunderous 423kW (or 575 horsepower, to Imperialists) and a massive 750 Newton metres of torque. That latter figure is 50 Newton metres beyond the design limits of the most advanced double-clutch gearbox that BMW could source, so the new M-cars' transmission is a conventional ZF eight-speed automatic instead. Well FAIRLY conventional, as the speed of the slam-dunk shifts is as quick as a double-clutch set-up and the spit-bang explosions on the overrun are artillery-like, and the thing that track-days are made of. 

Track days? In two-tonne plus SAVs? (That's Sports Activity Vehicles - BMW speak for SUVs).

Well, yes as it happens, for with a 4.2-second zero to 100kmh time - which could be repeated time after time by your granny if she had a heavy enough right foot. They also have an all-wheel-drive system that can divvy-out power and torque from what's normally  50:50 front to rear, to 100 per cent each way, these burly luxury bovver boys could vaccuum-up accepted track specialist cars with out drawing breath. And on a wet day, that pesky fairweather Boxster that was worrying your tail in the dry - but not getting past - would be a soggy speck in your mirror.

Unlike other X5 models, the ultra high-performance X5 M cannot be had with a third row of seats. Photo: Mark Bean/Fairfax NZ

That's not how we drive day to day though is it? But as with fifth dan black belts, it's nice to know you've got it, even if you seldom, if ever use it.

The X6 M and X5 M aren't all about performance, for as well that eat my dust thunder, the cars are remarkable in their everyday usability. They are quite happy to pootle along at part throttle during airport runs, daily commutes and even in the switchback taxi avoidance tasks you always get challenged with in Melbourne - as we witnessed last week. 

All it takes is a squeeze of the throttle to break free of snarls, and to throttle back to a quiet 100kmh cruise at 1700rpm in eighth gear. Drivers can tailor the driving experience to their preferences with Comfort, Sport and Sport+ settings for engine response, suspension settings and steering, while there's also Drivelogic function for the M Steptronic. 

You can save your favourite settings  and make them available for the task at hand with a single prod of an M-button. So while you might spend the first few days of owership getting to now all the nuances of suspension, engine and steering settings, you'll save your preferences as easily as you do with your smartphone.

A variety of colour combinations can be had with either of the M-cars, including this Crusaders special red and black number. Photo: Mark Bean/Fairfax NZ

The latest X6M and X5M BMWs seem in simple terms to be mechanically very similar to the vehicles they replace. They're still driven by twin-turbo 4.4-litre V8s, after all. But, like grandad's axe, the blade and handle have changed somewhat. 

In fact the engines' internals have been altered significantly, from initial intake tracts, right through the valves and cylinder heads, along with the cross-bank exhaust manifold, the twin-scrolled twin-turbochargers and the exhaust, from beginning to end. 

The exhausts now have tips that exit under the rear-splitter in ten millimetre wider, 90mm diameter, howitzer-like tips to help make that basso profundo exhaust note. The whole exercise was to imbue the new performance X-cars with better engine responsivess and efficiency. 

Simple figures tell the tale of BMWs' engineers' success, while the way the car crushes you to the upholstery is the more brutally physical evidence. 

That the engine now manages to sip fuel at family six-cylinder sedan like 11.1L/100km, compared with the previous cars' 13.9L/100km, even with all those power and torque improvements, is something of a miracle, but don't expect either the X5M or the X6M to do anything but gulp its fossil fuel when it's asked to perform.

Refettled engine uses Twin-Power technology to produce 423kW (575bhp) and 750Nm. Photo: Mark Bean/Fairfax NZ

Visually, the X5M and X6M have more scoops than a scandal sheet, with brakes that need to be cooled and ten heat exchangers to service the four cooling systems that rein-in the heat generated by and gained from the engine and the turbos, engine oil, the transmission and inter coolers. Shaped vertical side vents behind the front wheels scavange the heated air and gasses from the brakes and contribute to the 'air-curtain' that helps ease drag inducing slipstream disturbance around the wheelarches.

Standard 21 inch alloy rims now fill those wheel arches, shod with 285/35R21 tyres at the front and 325/30R21 tyres on the rear. The rubber is Michelin's Pilot Super Sport design, and BMW doesn't see a place for run-flat tyres on performance SAVs like the new Motorsport X-machines. 

For the first time, the X6 M gets a small rear spoiler, which we guess is in keeping with its slope-backed five-seat coupe styling. Nothing so crass is offered on the more sober-suited two-box X5 M. It's that wee spoiler that perhaps provides evidence as to the intended markets for the two cars. 

Despite many naysayers telling BMW that they were daft to create a sports coupe-cum-crossover with a fastback, the Munich-based concern, not for the first time, proved that they were right and we were wrong. This was illustrated by the fact that the initial production predictions for the first X6 was a total of 150,000 units, while BMW had to build 260,000 just to keep up with demand. 

This proved that there were people who liked the whacky, sporting bias of the X6 who probably found the X5 was too square, had too much practicality for their tastes, which required a rear seat if they must, and a car that shouted 'look at me' even when the engine was off and the car was parked.

So the addition of that spoiler is something of a punctuation mark for those usually younger buyers, unencumbered by children and who probably keep their dogs, if they have one, in a handbag. No self-respecting pooch would like the load area of the X6 M, though suitcases seem to.

The older punter is the X5 M person. They have friends and they have children, and or grandchildren and they prefer a design that'll take meaningful loads if they need to. The irony is that the X6 M and X5 M maintain that credo displayed by many a German carmaker that less costs more. 

They're as quick and loud as each other, just as capable on road and track and equally pleasurable to commute or cruise in, but the five-seater with the whacky roof is $212,800, while the squared-off and better looking (to this old mine), is 'just' $199,900. Oh and by the way, those 110,000 extra X6s that BMW had to make didn't gobble up X5 sales as some predicted, for that car had to be made in bigger numbers too.

BMW X5 M and X6 M

Drivetrain: In-line front-mounted, AWD, twin scroll, twin-turbo 32valve 4395cc quad cam V8, with 8-speed Steptronic automatic.

Outputs: Maximum 423kW/575bhp at 6000 to 6500rpm and a maximum 750Nm of torque at 2200 to 5000rpm.

Performance: Maximum 280kmh, 0-100kmh 4.2 seconds, 11.1L/100km, 258g/km CO2.

Chassis: Double-jointed spring-strut front suspension, integral rear axle with air suspension, electric power steering. six-piston front, single piston rear vented compound disc brakes, 10J x 21 front and 11.5J 21 rear alloy wheelrims.

Safety: Front, side and head airbags, DSC, ABS, cornering brake control, dynamic performance control, 5-star Euro NCAP rated.

Technology: IDrive, sat-nav, Bluetooth telephony and streaming, aux-in connection, television, heads-up display, 16-speaker Harmon-Kardon sound system, BMW connected drive services (some like TV and internet only with stationary car.

Dimensions: L X5 4880mm, X6 4909mm, H X5 1754mm, X6 1689mm, W X5 2184mm, X6 2170mm, W/base 2933, F/track 1666mm, R/track 1667mm, Weight X5 2275kg, X6 2265kg. Fuel 85L.

Pricing: BMW X5 M $199,500, X6 M $212,800.

Hot: Thunderous performance; balance and cornering poise; quality of interior, over-engineering power unit and transmission.

Not: X5's lack of third-row seating, X6's acquired-taste styling and rear headroom; inexplicable price difference.

Verdict: Porsche will be looking at uprating its Cayenne SUVs  in view of the M-series X-cars which move to the top of the SAV tree.