Nobody needs an SUV with over 600 horsepower. But that hasn't stopped BMW from making two of them for more than a decade now. Having first been introduced in 2009, the 2020 BMW X5 M and 2020 BMW X6 M emerge on the market in their third generations, facing stiffer competition than ever from the usual suspects like AMG and Porsche as well as new rivals like the Audi RS Q8.

We've sampled all manner of X5 and X6 variations ranging from the humdrum straight-six models and M-breathed M50i variants but the introduction of two new fully-fledged M variants warranted a trip to Phoenix to experience how these latest SUVs feel on Arizona's lovely mountain roads.

Exterior Design: Mean Machine

The X5 has always been a very handsome SUV with tall, upright proportions made sporty with an imposing, wide stance. With the latest X5 M, that wide stance could knock over an NFL defensive lineman. Passersby will notice something different about your X5 with its larger air intake openings, M specific BMW kidney grilles, M gills on the front fenders, flashy side mirrors, flared wheel arches, rear diffuser, and quad exhaust tips. And if all of those items don't tip them off, the car is festooned with M badges. Those who opt for the X5 M Competition (pictured here) will also get a rear roof spoiler.

Sitting on standard 21-inch wheels or optional staggered (22-inches in the back) wheels on the Competition model, the X5 M looks properly aggressive whether it is lapping a racetrack or sitting in the school pickup line. Those tires measure 295 mm in the front and 315 mm in the rear, making the front and rear of the car look especially wide. BMW only had Mineral White Metallic and Tanzanite Blue II Metallic on hand for us to drive but more wacky hues like Manhattan Green Metallic and Ametrin Metallic (a dark purple) are available.

Engine, Performance, & MPG: Brutal In Every Sense

Under the hood lies BMW's 4.4-liter twin-turbocharged V8, codenamed the S63, which also lives under the hood of the M5 and M8. Here it produces 600 horsepower at 6,000 rpm and 553 lb-ft at 1,800 to 5,690 rpm (an increase of 33 hp over the last-generation). If you opt for the X5 M Competition, the output is upped to 617 and the torque is available at a broader rpm range from 1,800 to 5,860 rpm. The non-competition model completes the sprint to 60 mph in just 3.8 seconds while the Competition model does the deed a tenth of a second quicker.

Power is always routed through an M Steptronic eight-speed automatic transmission to xDrive all-wheel-drive with an Active M differential. The top speed, like most German cars, is limited to 155 mph but can be increased to 177 mph with the M Driver's Package. Opting for this package also gets you lessons at one of BMW's performance driving centers where you can learn to harness the abilities of your 600-hp SUV. The price to be paid for this overwhelming performance comes at the pump where the EPA rates the X5 M at 13/18/15 mpg city/highway/combined.

Interior Design: Sporty Elegance

The M Division had a great starting point with the X5. The biggest change on the X5 M is the addition of M multifunction seats, which hug you more than a standard X5 chair. These seats look great but do come with a slight trade-off in comfort. That being said, they can still be optioned with heating, ventilation, and massage functions and can feel much more forgiving than the seats found in the X3 M and X4 M.

Other changes to the cabin include carbon fiber trim, illuminated door sill plates, M control buttons on the center console, an M-specific shifter, and M stitching. Opting for the Competition model adds extended leather on the dash and knee padding and M stripe seatbelts. BMW's iDrive 7.0 is frankly excellent, though it isn't the easiest system to hop in and use on the fly.

Trunk & Cargo Space: Room A-Plenty

Just because the X5 M can tear up a race track with ease doesn't mean BMW wanted it to be any less practical than a standard X5. The 117-inch wheelbase accommodates 37.4 inches of rear legroom, which should be fine for most average-sized adults. Rear headroom is equally generous with 39.4 inches of space. Behind the rear seats, the X5 M can accommodate up to 33.9 cubic feet, meaning your kids soccer equipment will fit with ease along with the family dog. Folding down the second row can be done 40:20:40 style using two easy levers in the cargo area or using pullies on the seats, opening the storage space up to a generous 72.3 cubic feet.

Driving Impressions: Hardcore With A Soft Side

With 617 hp on tap, it should be no surprise that the X5 M feels savagely quick in a straight line but the car feels even more impressive through the bends. The M xDrive system sends most of its power rearward, only shifting to the front wheels when it senses a loss of traction. We recommended the inclusion of a rear-wheel-drive burnout mode for the American market but BMW's engineers didn't seem too entertained by the idea. So even when you pitch the X5 M around a corner that clearly looks too tight, it grips and comes out on the other side completely unphased.

The Adaptive M suspension Professional with Active Roll Stabilization keeps the body lean to a minimum at a meager cost to comfort. Over rough pavement, the ride can feel a bit busy but nowhere near the jarring, head-pounding experience of the X3 M and X4 M. The X5 M still offers a cushy ride on the highway with a dull roar from the wide tires acting as a subtle reminder that you are at the helm of a 617-hp battleship.

A hard-edged weapon the X5 M might be, but it is slightly lacking on driver involvement. The M Servotronic speed-sensitive, variable-ratio steering has two selectable drive modes (one for comfort and one for sport) but neither provided us with the feedback we expect out of an M car. The rack was quick to respond to all of our inputs but it was a one-way conversation with none of the imperfections and undulations in the road coming back through the wheel.

We felt the same way about the M Compound brakes, which also feature Comfort and Sport modes. The brakes feature an electric actuator that builds up pressure and maintains an even brake pedal feel but without providing much communication (though the brakes felt much less grabby than other performance calipers). Under more high-pace conditions, the 395 mm front disks with fixed six-piston calipers bring the car to an abrupt halt with a more pleasant response than in normal traffic conditions.

Our only other gripe was with the M Sports Exhaust, which wasn't loud enough inside the cabin for our tastes. An aftermarket system will fix that problem up in a hurry.

Price & Trims: Just Get The Competition

Pricing for the 2020 X5 M starts at a whopping $105,100 (plus $995 destination), so you won't be seeing one in every neighborhood cul de sac. $9,000 more nets you the Competition model for $114,100, adding 17 hp, an M Sports Exhaust, staggered wheels, M seatbelts, and extended leather. To be fair, there are other ways to spend $9,000 on options but with a well over six-figure investment, we doubt too many buyers will quibble over the decision. We didn't have a chance to drive the standard X5 M but on the off chance a Competition model pulls up next to you at a set of lights, you won't want to be left a tenth of a second behind. At this price level, just opt for the Competition.

We spent the day driving a Mineral White X5 M Competition equipped with the Drivers Assistance Pro Package ($1,700), Executive Package ($3,600), Bowers & Wilkins Sound System ($3,400), and M Driver's Package ($2,400), bringing the as-test price to $126,925.

Verdict: Unnecessary, But Awesome

Driving purists will undoubtedly scoff at the idea of a 5,425-pound SUV with an M badge but if you showed the X5 M a starting grid filled with legendary M models like the M1, E39 M5, and E46 M3, we're sure it would leave those "pure" cars in the dust. As much as we'd like to see the M Division engineer more feedback into the steering, it would likely ruin the X5 M's road manners as an SUV, decreasing its appeal to the majority of buyers. Those looking for a more involved driving experience who don't need the space should look to the smaller X3 M.

The X5 M strikes a balance between livable everyday comfort and practicality with the option of taking it to a race track. Most buyers, the vast majority, in fact, will be perfectly content with the X5 M50i, which uses a detuned version of this engine producing 523 hp. But for those who live life a quarter-mile at a time with a family's worth of stuff in the back, the X5 M could be for you.