The BMW M8 makes one hell of a first impression. A bright red M8 Competition Coupe lurking in the pit lane at Portugal's Portimao Circuit is equal parts elegant and imposing. Under the hood there's a twin-turbocharged V8 with 617 horsepower, allowing for a 3-second 0-to-60-mph acceleration time. It's a big car with big power. And Portimao is the perfect place to put it through its paces.All M8s use the same engine: BMW's 4.4-liter, twin-turbo S63 V8. In the standard M8, it produces 600 horsepower and 553 pound-feet of torque. Opt for the more expensive Competition model tested here and you get the aforementioned 617 hp, but the same 553 lb-ft. Regardless of output, the M8 uses an eight-speed automatic transmission with steering wheel-mounted shift paddles. All that brute force runs to the ground via a rear-biased all-wheel-drive system, which can torque-vector across the rear axle for improved cornering grip.The M8 Competition will set you back $146,000 -- a $13,000 increase over the standard M8 Coupe. But you do get more than just an additional 17 hp for that not-insignificant upcharge. The Competition pack also adds unique 20-inch wheels, an M Sport exhaust, different-colored seat belts (for whatever that's worth) and a Track profile for the M drive settings. Track mode completely disables all driver-assistance systems and turns off the radio and center infotainment display. The 12.3-inch digital gauge cluster and head-up display (HUD) go minimalist in this setting, as well, only giving the driver the most important information they need.Now, one small caveat: While a plump gallery of sunny summertime on-location photos accompanies this review, they were actually taken a few days before my track test. When I showed up at Portimao on a Saturday morning in September, it had just rained, with bits of drizzle and mist still in the air. Not exactly ideal track-day conditions, but as I soon discovered, the wet weather afforded many opportunities for me to experience the sophisticated driveline tech found in the new M8.By the time you cross the start\/finish line after a reconnaissance lap, the M8 is already carrying a tremendous amount of speed. And as you head down the hill toward Turn 1, the car's rump squirms a little while you trailbrake into the corner, before rolling back on the throttle through Turn 3 (BMW's track configuration bypasses Turn 2). Meaty, 15.7-inch carbon-ceramic front discs allow you to scrub off a ton of speed while braking late before Turn 4, which sits at the bottom of a hill, and the pavement is especially wet. Even with the traction control fully enabled, the rear-biased all-wheel drive allows for plenty of back-end slip through this corner. On later laps, while switching to the less aggressive 4WD Sport setting, you can hold a long slide as you make your way up the hill toward Turn 5. As on the four-door M5, the M8 has a dedicated two-wheel-drive mode, but considering how much freedom the 4WD Sport setting gives you, I wouldn't want to use it in these wet conditions.A quick word about those brakes: While there's no arguing against the goodness of the powerful carbon-ceramic setup, I'm not totally sold on the brake-by-wire tech BMW's fitted to the M8. It's not even half as bad as the horribly tuned version of this setup Alfa Romeo uses in the Giulia and Stelvio, but there's still some weirdness to the feeling you get through the pedal. To its credit, BMW says the brake-by-wire tech saves about 4.5 pounds over a conventional setup, and allows drivers to change between Comfort and Sport settings, varying the brake pedal and amount of feedback. But in my experience, the two systems sort of feel like a wash, and weight savings aside, this feels like a solution to something that isn't actually a problem. I can't recall any recent BMWs having unsatisfactory brakes; why fix what isn't broken?Turn 6 is just like Turn 4, and the automatic transmission eagerly downshifts under braking as you approach this left-hand hairpin. Small inputs through the thick-rimmed, heavy steering wheel allow you to nicely string together Turns 7 and 8, before a quick dab of brakes before going left into Turn 9. I love the weight of the M8's steering, and how quickly the front tires respond to action. But like the 8 Series Gran Coupe, I'm left wanting a bit more feedback, especially on-center.The V8's midrange punch is ample for accelerating up the hill to Turn 10, and I love how eagerly the automatic transmission holds gears all the way up to redline as I head toward Turn 11. At Turn 12, the 4WD Sport mode again allows for a bit of slide as I coast down the hill toward Turn 13, and the exhaust roars as I roll back onto the throttle before another late-brake entry into the Turn 14 hairpin. Through Turn 15 and the long sweeper that is Turn 16, progressive throttle inputs keep the M8 stable, and it's wet enough that I'm thankful for the standard xDrive mode's four-wheel traction. All the while, even in the rain, the M8 feels totally unflappable, like it has so much more to give. Great as the M8 Competition Coupe is while lapping Portimao, I can't speak to its public-road prowess. Instead, that's where I got to experience another part of the M8 portfolio: the Convertible, which is also offered in base and Competition guises, for $142,500 and $155,500, respectively. The last chapter in the M8 story, the Gran Coupe, Gran Coupe, will debut at the 2019 Los Angeles Auto Show in November. And much like the standard 8 Series Gran Coupe, expect this body style to account for about 50% of all M8 sales. At $130,000 to start, it'll be the cheapest M8 of the bunch.Aside from, you know, the roof, the M8 Convertible is no different from the M8 Coupe. It's about 265 pounds heavier than its hardtop equivalent, and BMW says this results in a very small reduction in initial acceleration time. Still, I'm talking about a big, four-seat convertible that can scoot to 60 mph in as little as 3.1 seconds, so don't for a minute think that the droptop gives up any real performance to its coupe counterpart.On the hilly Portuguese roads between the Portimao circuit and my hotel near Faro, the M8 is a stunner, even on this chilly, damp day. The Competition spec might be the most hard-core, but in Comfort mode on smooth highways, the ride quality is supple. Change it to Sport or Sport Plus and the difference is minimal, the M8 once again never sacrificing grace despite tremendous cornering poise.With the top up, the M8 Convertible is perfectly cozy and quiet. With the top down, however, it's surprisingly loud. While other modern convertibles do a great job of channeling air around the cabin to disrupt the passengers (and their hairdos) as little as possible, the M8 doesn't really excel here. At 70 mph on the freeway, I have to shout just to have a conversation with a guy sitting less than a foot away from me -- and that's with the side windows up.Nevertheless, just like in every other 8 Series model, the M8's cabin is absolutely exquisite. From the quilted leather on the cushy, supportive seats, to the high-quality metal finishes on the dashboard and center console, this is a cabin that oozes class. In the convertible, BMW offers a neck warmer, similar to Mercedes' Airscarf feature, which channels warm air through the seat and out a small vent just below the headrest. If you ever plan to drive your M8 with the top down on a crisp fall day -- and you should, that's the best kind of convertible weather -- this is a must-have option.The M8's cabin tech carries over from the rest of the 8 Series range, meaning you get BMW's latest iDrive 7 infotainment system housed on a 10.2-inch central display. You can control iDrive via the knob on the center console, by speaking voice commands or simply touching the screen. And while the menu structure can sometimes be a bit hard to navigate, I have to commend iDrive for its quick responses to input and its incredible functionality. BMW's artificial intelligence tech makes this a robust system -- just say, "Hey, BMW" to access a number of connected-car functions. And while all M8s feature Apple CarPlay compatibility, I'll once again point out that it doesn't have Android Auto. (I'll stop mentioning that when BMW starts including it.)In typical BMW fashion, there are a number of driver-assistance systems available, but most of them will cost you. You only get forward collision warning with automatic emergency braking as standard equipment. If you want blind-spot monitoring, lane departure warning, a surround-view camera, parking assistant, rear cross-traffic alert or full-speed adaptive cruise control, you'll have to pony up for one of BMW's option packages. Considering these are $130,000 cars we're talking about, that's nickel-and-diming at its finest.But really, the M8 itself is an exercise in upselling. The M8 Competition is an admirable performer, but most buyers won't ever take their cars to the track, and the 17-hp upgrade and additional Track mode won't make a difference to them on the street. That leaves you with the standard M8, which in itself seems like a great package, but I'm not sure it's a big enough step up from the lovely M850i, which uses the same 4.4-liter V8, but with 523 hp instead of 600. Without driving the cars back to back, it's hard to say if the M8 exhibits a noticeably more aggressive on-road demeanor -- at least, one worth paying an extra $21,100 for. If you have the cash, the M8 is a seriously appealing package, even if it just speaks to the inherent greatness the 8 Series has at its core. Editors' note: Travel costs related to this feature were covered by the manufacturer. This is common in the auto industry, as it's far more economical to ship journalists to cars than to ship cars to journalists. 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