The Ford Mustang Dark Horse is a car that's got everybody talking in the automotive world right now. That's not surprising, as it's easily one of the best muscle cars on sale today. It gets 500 hp from a performance-tuned 5.0-liter Coyote V8, and lots of gearheads who've driven or owned one have absolutely loved the experience. But the Mustang Dark Horse does shout a lot about what it's capable of. It's a very aggressive-looking car, and some buyers might want something a bit more understated.The following ten sleeper cars provide similar performance to a Mustang Dark Horse but in a much more unassuming and practical package. This under-the-radar approach makes them arguably just as cool, especially since they'll outrun many sports cars at the traffic light. Our list includes everything from luxurious sedans to under-the-radar American muscle cars. All of them are perfect alternatives to Ford's new benchmark muscle car.All performance specs and information come from the respective car manufacturers. We also used Car and Driver's official real-world tests for 0-60 mph times. Lexus IS500 F-Sport Performance Specs Source: LexusLexus isn't a brand you'd typically associate with fire-breathing, high-performance cars. But, Toyota's luxury arm has given us quite a few models like that! One of the latest of those is the IS500 F-Sport Performance. While this isn't a true IS F, it's the closest thing we'll ever have to getting another one. It has a 5-liter naturally aspirated V8 like the Mustang Dark Horse, although its engine is slightly less powerful at 472 hp. That doesn't mean it's a slouch, though, as it can accelerate from 0-60 in just 4.4 seconds!The "F"-branded Lexus models have always been seen as a more intelligent, understated or quirky choice when it comes to high-performance premium cars. The IS500 F-Sport Performance absolutely lives up to that reputation. It's as fast as any decent American muscle car, yet a lot of people won't know how tire-shreddingly powerful it is just by looking at it. It's one of the biggest sleepers on the market right now, and now would be a good time to go out and buy one before Lexus stops making cars with naturally aspirated V8s. 2020 Alpina B7 xDrive Cars & Bids Specs Source: AlpinaAlpina is the quiet and often forgotten end of BMW's performance machines. Originally an independent tuning house much like Brabus, it's now fully owned by BMW. Taking a very different approach to the M Division, Alpina takes a more luxurious and understated approach to delivering the same kind of massive performance.Perhaps one of the ultimate expressions of the Alpina way of doing things is the B7. This car is powered by BMW's venerable 4.4-liter twin-turbocharged V8. Alpina's breathed on it a bit, though, getting it up to 599 hp and 590 lb-ft of torque. The result of that is that this big, luxury sedan can accelerate from 0-60 in 3.6 seconds. It'll also go on to hit a limited top speed of 193 mph on North American versions of the car. With the limiter off, it can go as fast as 205 mph, making it faster than a Dodge Hellcat.The Alpina B7 is possibly one of the world's greatest sleeper cars. It looks every bit like the luxobarge it's based on, with only bigger wheels and some subtle body changes giving the game away. The only thing that would give away how fast it is to the casual observer is if it roared off into the distance in front of them. Audi S8 Plus (D4) Bring a Trailer Specs Source: AudiLike the Alpina B7, the Audi S8 Plus is a big luxobarge with a surprising amount of performance. While it may not have the glorious V10 engine of older S8 models, the S8 Plus of the late 2010s more than make up for that with its 597 hp and 190 mph top speed. That's more than enough to keep up with a Ford Mustang Dark Horse, in a package that's much more discreet. The Audi S8 looks barely any different to the regular A8, so a lot of people would be genuinely surprised if you floored it.In many ways, the Audi S8 is like the Alpina B7 mentioned earlier. It's a big, traditional luxury sedan, with massive power in an understated package. The only thing that would give away how fast it is to most people is if it beat a Ford Mustang, Dodge Challenger or even a Porsche 911 at the lights. Alpina B5 (G30) Specs Source: AlpinaThe second Alpina on this list, the G30-generation (2017-2023) B5 is the legendary BMW tuning arm's equivalent of the M5. Like many BMW models, it uses the tried and tested 4.4-liter twin-turbo V8. It's tuned the same way as the V8 in the B7, producing 599 hp and 590 lb-ft of torque. This turns the regular 5-series the B5 is based on into an absolute monster, capable of reaching speeds of up to 205 mph. But, unless you know about Alpina, you'd never know. From the outside, it just looks like a regular 5-series with fancier wheels and bodywork.There are quite a few people who prefer the Alpina B5 over the BMW M5. With how much of a sleeper it is and how it's got a more luxurious focus than the M5, that's understandable. If that wasn't enough, it's also available as a station wagon (known as the B5 Touring). This easily makes it the most practical car on this list. You can have something just as fast as a Ford Mustang Dark Horse, but you'll be able to bring your kids and/or dog along for the ride too! Alpina B8 Gran Coupe (G16) bmwusanews.com Specs Source: AlpinaThe third of four Alpinas on this list, the B8 Gran Coupe is it's take on making a super fast version of the 8-series Gran Coupe. It's got the same 4.4-liter V8 as the B5 and B7 mentioned earlier. The B8 Gran Coupe gets more power, though, with 621 hp instead of 599 like the B5 and B7. This makes it much more powerful than the Ford Mustang Dark Horse, and that 4 door body style makes it more practical too.The Alpina B8 Gran Coupe definitely lives up to Alpina's reputation of producing plusher takes on the high-performance BMW. It's a comfortable, smart-looking car that'll deliver performance that'll humble most proper sports cars and muscle cars. It'll also go almost completely under the radar. Only the people who know the Alpina brand will know what this car's capable of. 2012-14 Chrysler 300C SRT-8 Specs Source: ChryslerThere are plenty of sedans out there with V8 muscle car power. The Chrysler 300C SRT-8 is one of those. Unlike other muscle sedans such as the Dodge Charger and the AMG-badged Mercedes sedans, the Chrysler 300C SRT-8 goes far under the radar. That's a bit of a shame because this car is ludicrously powerful for its fairly ordinary (and somewhat chintzy!) appearance. Its 6.4-liter V8 produces 470 hp and 470 lb-ft of torque, enough to take it from 0-60 in 4.5 seconds. That makes it more than capable of matching the Ford Mustang Dark Horse when it comes to performance.Cars like the Chrysler 300C SRT-8 won't be around for much longer. We should enjoy them while they're still around. Most people would see the 300C SRT-8 and think it's just another slightly garish-looking American sedan. They wouldn't guess what kind of insanity lies under the hood. Alpina B3 (G20/G21) YouTube - carwow Specs Source: AlpinaThe fourth (and final) Alpina on this list is the B3. Yet again, this is an alternative, more luxurious take on a high-performance BMW. Unlike the B5, B7, and B8 Gran Coupe mentioned earlier, this isn't powered by a V8. Instead, it's powered by a tuned-up version of BMW's well-used 3-liter turbocharged inline-6. In the G20 generation Alpina B3, this produces 461 hp and 516 lb-ft of torque. That's enough for a top speed of 190 mph, easily eclipsing the Mustang Dark Horse.The coolest part about the B3, though, is that it's available as a station wagon like the B5. While it's smaller than the B5 Touring, the B3 Touring is still a very practical performance car. You can get almost all the junk you could possibly ask it to carry into the back and still have an absolute riot thanks to its brilliant performance. 2005-2009 Cadillac STS-V Bring A Trailer Specs Source: CadillacMany people know about Cadillac's V-Series cars. The CT5-V Blackwing has become famed for its incredible performance (and its insistence on keeping a manual transmission option), and the CTS-V that came before it has garnered a great reputation for how fantastic its performance is.One of Cadillac's V cars that gets seriously overlooked, though, is the STS-V. The high-performance version of the STS luxury sedan, it could be easy to overlook it at first glance. It looks barely any different from the standard STS. But, beneath those understated looks is a serious performance car. It's powered by a supercharged version of Cadillac's Northstar V8. This engine produces 469 hp and 439 lb-ft of torque. That's enough to take the STS-V from 0-60 in 4.6 seconds.The Cadillac STS is an intriguing American alternative to cars like the Audi S8 and Alpina B7 mentioned earlier. While it may not be as high-quality as its European rivals, its performance is definitely on par with them. It'll easily keep up with the Ford Mustang Dark Horse while keeping you comfortable in the best American luxury available in its day. 2016 Chevrolet SS Chevrolet Specs Source: ChevroletThe Chevrolet SS is one of General Motors forgotten performance car experiments. A captive import version of the Holden HSV Commodore for the American market, this muscle sedan has a 6.2-liter V8 borrowed from the Corvette. This engine produces 415 hp and 415 lb-ft of torque, enough for a 0-60 time of 4.5 seconds and a limited top speed of 160 mph. That makes it easily capable of keeping up with a Ford Mustang Dark Horse, or indeed many current sports cars.The Chevrolet SS is a car that only the biggest gearheads seem to remember. If a regular member of the public saw it in person, they'd just think it was a regular Chevrolet sedan. The only thing that might give away what kind of power is under the hood is the burble of its LS V8. Kia EV6 GT US Spec - 2023 Kia EV6 GT Front Three Quarter Specs Source: KiaThe Kia EV6 GT is a real curveball in this list. Not only is it the only car here that could be considered an SUV, but it's also the only one that's electric! While it may look like a fairly sedate crossover from the outside, the EV6 GT becomes a menace when you put your foot down. Its 577-hp dual-motor drivetrain gets it from 0-60 in 3.2 seconds. That makes it much faster than a Ford Mustang Dark Horse, until you get to higher speeds. It's also much more practical than the Mustang Dark Horse and will cost you a lot less to run, thanks to being electric.The gradual transition to electric has worried some people. There have been a lot of concerns that proper performance machines will die out. The Kia EV6 GT not only disproves this, but it also disproves that we won't have crazy fast sleeper cars in an all-electric future.