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A massive V8 is a trademark of almost every true muscle car. However, the modern automotive era has shifted away from large-displacement, gas-guzzling, naturally aspirated V8s to downsized, hybridized, and forced-induction engines to save fuel and reduce harmful emissions. Although we used to associate huge power with huge displacement, this is no longer the case; some relatively tiny engines are now capable of pushing massive power.

Engines like the Chevrolet 396, Chrysler 426 HEMI, or Pontiac 455 Super Duty are some of the most iconic engines from the golden era of muscle cars, and most variants of these typically push between 375 and 450 horsepower. With displacements ranging from roughly 6.5 to 7.5 liters, that gives a liter-to-horsepower ratio of only about 60–64 hp per liter. Although numbers are not everything when it comes to performance cars, they do play a significant role. 

Even the 2024 Ford Mustang GT, with its equally coveted 5-liter Coyote V8, is good for 480 horsepower, or about 96 hp per liter. If we also consider hybridized engines with twin-turbocharged setups, some modern powertrains can both eclipse the horsepower of those old-school 7-liter V8s while being far more efficient and emissions-friendly. Here are four small engines with more power than muscle car V8s.

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The W204 Mercedes C63 AMG is likely the closest thing to a European muscle car you are ever going to get. Thanks to its 6.2-liter naturally aspirated V8, the W204 sounds, feels, and goes like a muscle car. The newest model, the W206 C63 AMG S E-Performance, is an entirely different car. Powered by a 2-liter turbocharged M139 four-cylinder inline engine with 469 horsepower and 402 lb-ft of torque, it is one of the most powerful 4-cylinder engines ever made. However, this engine is a hybrid.

When also accounting for the 4.8 kWh high-voltage battery pack with a rear-mounted electric motor, the C63 S E-Performance tops out at 671 horsepower and 752 lb-ft of torque. From a liter per horsepower ratio, the M139 engine alone is rated at 235 hp per liter, an extreme output level that is almost four times higher than the Chevy 396, HEMI 426, Pontiac 455, or more than two times than that of the Ford Mustang GT’s Coyote 5.0.

Even the absolutely insane new 2025 Corvette ZR1’s 5.5-liter turbocharged V8 with 1,064 horsepower is only 193 hp per liter. The range-topping ZR1X hybrid Corvette engine also uses an electric motor for a combined 1,250 horsepower (227 horsepower per liter). Meanwhile, the Mercedes 2-liter M139, when accounting for the electric motor, pushes an astonishing 335.5 horsepower per liter. Yet despite its performance, many enthusiasts believe the M139 hybrid to be one of the worst Mercedes engines ever made, simply because it just does not offer the same excitement as a naturally aspirated V8.

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Volvo is not necessarily known for making the world’s most powerful, performance-oriented engines, but the inline four-cylinder you find in the Volvo XC60 T8 is indeed impressive. With a displacement of just 2.0 liters, this engine is both supercharged and turbocharged, producing 328 horsepower and 330 lb-ft of torque all on its own.

This small Volvo powerplant is capable of a liter-to-horsepower ratio of 164 hp per liter — already more than the Coyote 5.0 in the Mustang GT. Being a plug-in hybrid, it also uses electric motors and an 11.6 kWh high-voltage battery pack, which brings the total system output to 415 horsepower and 494 lb-ft of torque, giving a combined 207.5 horsepower per liter — three times more than the iconic muscle car engines from the golden era.

With such a massive output, Car and Driver notes the XC60 T8 can still return around 26–28 MPG combined, which is equally as impressive. Not long ago, we said that the 2025 Volvo XC60 makes sense as a hybrid because it is a usable, high-power hybrid SUV that doesn’t compromise daily practicality. What makes this engine even more impressive is that it was never really used on high-performance vehicles, unlike the other engines on this list. 

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The Porsche 911 GT2 RS is the top-spec Porsche 911 track-focused model. Its performance sees it standing above the coveted GT 3 and the iconic GT 3 RS. The GT 2 RS uses a similar engine to the Porsche 911 Turbo S, a twin-turbocharged 3.8-liter boxer six-cylinder engine that pushes out a total of 690 horsepower and 553 lb-ft of torque. This makes this engine the most powerful production flat six at time of writing. Meanwhile, the GT 2 RS pushes out 182 horsepower per liter, an impressive total output for an engine that isn’t even hybridized.

The upcoming 992 generation of the GT 2 RS is expected to also get a hybrid battery on top of its flat-six, meaning that the total combined output could rise to 750 horsepower. The Porsche 911 might just be the best high-performance car you can buy right now, and the GT 2 RS is the king of the entire lineup. This engine also enabled the GT2 RS to run the Nürburgring Nordschleife in just 6 minutes and 43 seconds, making it one of the fastest production cars to ever go around the famous track.

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Although the 911 GT2 RS does feature the most powerful flat six engine, it’s the upcoming Ferrari F80 hypercar — the successor to the LaFerrari — that uses the most powerful factory-installed six-cylinder of any kind. This very cutting edge engine from the Italian automaker is a 3-liter 120-degree twin-turbocharged V6 that makes 888 horsepower and 627 lb-ft of torque. In total, this gives this Ferrari a horsepower per liter ratio (just the engine) of 296 horsepower per liter — one of the highest figures ever seen in a production car.

However, Ferrari went a step further and paired the F80 with electric motors and a 2.28 kWh high‑voltage pack for a combined system output of 1,184 horsepower. This comes out to 394 horsepower per liter — more than some muscle car V8s make with their full 7‑liter displacement. However, with a price tag of $3.75 million, the F80 is limited to only 799 examples, and not everyone can just walk into a Ferrari showroom and order an F80.