No one likes that guy in the red Ferrari who revs his engine the whole time he's stopped at every red light. It's clear he's got some compensating to do—and the money to do it—but every gearhead gets a little heartbroken to see beautiful sports cars serving as little more than ego-boosters for the uber-wealthy.
Not many enthusiasts will ever get to drive a Ferrari at any point in their lives and even fewer can even dream that they'll one day own the cars they pinned up on their bedroom walls as kids. Even if, by some miracle, a lucky duck manages to get hold of a cool million bucks, would they really spend a quarter of their fortune on a brand-new, 600-horsepower stallion with two pedals and an F1 automated manual? Probably not.
And yet, every gearhead dreams of one day having the funds, the time, and the knowledge to build their own car. Maybe it won't look like much—and the chances of it actually being faster than a Lamborghini Veneno are, face it, slim to none—but it'll be their own sweet, precious baby. And with all the resources in the world now available with the click of a mouse and a few taps on the keyboard, the general public's ability to create serious automotive power has never been greater.
Plenty of tuners and modders out there have beefed up their Civics and Subarus to wild power levels but they also seem to spend just about as much cash on body kits and stance as they do on actual performance upgrades. But real gearheads know that the interior and exterior come last; first and foremost come power and handling. Enter the sleeper phenomenon—cars that look boring but hide big secrets under their understated skin. That Ferrari driver will never see these sleepers coming, but he'll be forced to watch them go.
20 Chevy SS
The Chevrolet SS leaves the factory in pretty solid sleeper configuration. Most drivers on the road might easily mistake it for a boring Malibu or Cruze, though if they tried to pull away, they'd likely get the surprise of their life. This particular SS is even more radical. Its owner decided to try to make the world's fastest SS and there's little doubt that he reached that lofty goal.
With a supercharger bolted on that would make the guys at Hennessey giddy with excitement, this SS can now run 10.99-second quarter miles at a trap speed of 129.11 miles per hour. The supercharger pushes 11.5 PSI, so even at low speeds, torque should be plentiful to allow for sub-four second 0-60 times.
19 Chevrolet S-10
No one glances at a boring old 2000 Chevrolet S-10 and thinks it's a performance car. This boring compact pickup looks more at home in a Lowe's parking lot—even with those slightly flashy wheels. But even with rims that shiny, this S-10 still qualifies as a legit sleeper thanks to a 5.3-liter V8 swapped in (in place of its stock 4.3-liter V6).
Throw on a turbo pushing low boost and this tiny truck's rear tires look appropriate all of a sudden because it's pushing up to 783 horsepower and 609 lb-ft of torque. It might need sandbags in the bed to keep that rubber from burning out!
18 Audi RS6 Avant
The Audi RS6 is a little-known model here in the US, especially in the Avant trim that was never shipped to these shores. Even a stock RS6 is a sleeper from the factory thanks to a twin-turbocharged V8 engine and Audi's legendary Quattro all-wheel drive. Audi didn't even have a manual trans that could handle all that power, so the RS6's major flaw is a five-speed auto with tiptronic.
This specific RS6 Avant was imported to the US by the late Paul Walker and it has received a GIAC ECU tune that should easily bump power up significantly from the base 444 horsepower and 428 lb-ft of torque.
17 Opel Omega Wagon
This is one epic sleeper that almost loses its status due to its wheels and a set of four exhaust tips peeking out the bottom of the rear bumper. (The Speedhunters window decal doesn't help, either.)
In the end, though, it's saved because it's a strange mishmash of an Opel station wagon and another Opel-based product, the epic Lotus Carlton. A dream car that never made it to the States during its production run, the Carlton was popular with criminals trying to avoid the law. This wagon would be even better because its base Lotus engine—a twin-turbocharged, 3.6-liter V6 cranking out 377 horsepower—has been stroked to 3.9 liters and received a Garrett GT4202R single turbo to produce up to 878 horsepower and 800 lb-ft of torque.
16 Volvo 850 R
The former owner of this Volvo 850 R knew a thing or two about riding around incognito. He was a celebrity who loved motorsport but knew that driving around Hollywood with one of the world's most recognizable faces shining out of a supercar like a Ferrari would attract too much attention.
And so, Paul Newman turned to Ross Converse to drop a Ford V8 under the hood of his boxy mom-mobile, and the 5.0-liter unit was further upgraded with a Kenne Bell supercharger. The 380 horsepower and 400 lb-ft of torque are routed to the ground through a Mustang-sourced Tremec T5 six-speed. Sometimes a Volvo station wagon can be a pretty cool hand.
15 Toyota Camry
This car may be the ultimate sleeper. Sure, that term gets thrown around a lot—but this may just have reached peak sleeper. On the outside, the car looks like a factory Toyota Camry. In reality, that's not fair because everything that turned it into a super-sedan was done by TRD, themselves.
Under the shell, just about everything has been changed, including swapping in a 5.7-liter V8 from a Toyota truck and adding a supercharger and nitrous system that combine to pump out 850 horsepower. Maybe—possibly but probably not—an eagle-eyed gearhead or two might notice the intercooler behind the front grille. That's only if anyone ever sees anything but this Camry's taillights, though.
14 Saab 9000
Saab rides from the 1990s are the perfect candidates for sleeper builds. The Swedish automaker was still building bulletproof engines during that era, and their products are famous for being able to handle serious power at an affordable price. The b234 engine, especially, is famous for being able to pump up in excess of 600 horsepower.
Even on stock internals, the ECU is smart enough to delay either timing or boost to keep the engine from knock symptoms, and this owner claims having reached 666 horses, no problem—even with an auto transmission still in place to route all that power to the ground.
13 Audi S4 Avant
Audi cars are perfect building blocks for sleeper builds because the manufacturer has such a long history of combining Quattro all-wheel drive with beefy, turbocharged engines. Case in point is a ubiquitous tuner favorite, the B5 S4.
This B5 S4 Avant goes one step beyond most builds, though, with a swapped-in 3.0-liter RS4 engine benefiting from a Garrett GT3086 turbo setup to crank out a claimed 1,200 horsepower. And other than the bigger wheels—which have become standard fare for Audis these days, anyway—no one suspects that the kids in the back seat might be having the ride of their lives.
12 Subaru Legacy GT
Plenty of Subaru fanboys create ridiculous ricers out of their Imprezas, be they in WRX or STI trim. And Subarus are a great starting point for a fun, affordable, easy to work on project—but the styling of the Impreza over all its generations makes it look like a tune-job even from far away. The Legacy GT is a much better exterior for a sleeper, especially since under the skin, it shares plenty of mechanical components with the STI.
Throw on a Cobb ram air intake and tune, as this owner has, along with an Invidia cat-back exhaust, and 0-60 times under four seconds come down to the driver's shifting skills more than anything else.
11 Ford Fairmont
The only things that give this Ford Fairmont away as being a serious sprinter are those wide drag slicks out back. Otherwise, it's difficult to think of a more boring sedan than this exact four-door in this exact shade of bland brown.
A nickname like "Leroy Brown" reveals that this car's owner knows exactly what they're getting up to, and builder Matt Happel tossed a 4.8-liter LS V8 under the hood and bolted on a big, single Borg Warner S480 turbocharger. With around 15 PSI of boost, the car can churn out quarter miles in the 8-second realm despite its heft and complete lack of aerodynamics.
10 Volvo S60 R
Most people think of Volvos as those perfect family cars from Sweden: safe, practical, and reliable. But secretly, Volvo has consistently turned out some pretty impressive performance vehicles, some of which qualify as sleepers for the simple fact that they mostly look like the rest of the Volvo lineup.
Take the S60 in R trim, which left the factory with a 300-horsepower, turbocharged inline five engine that sent power through a six-speed transmission and Haldex-sourced all-wheel drive. Many owners opt for a simple ECU tune, which can spread out low-end torque and pair with the all-wheel drive to make for a seriously quick sprinter.
9 Mercedes-Benz CL600
Everyone knows that Mercedes-Benz makes luxury cars worthy of their tremendous prices. And their reputation as a builder of reliable vehicles doesn't hurt sales, either. But in recent years, as with many luxury builders, the trend towards massive depreciation has hit hard.
This Mercedes-Benz CL600 looks like just another coupe at first glance, but it qualifies as a legit sleeper. This model can be found easily on the used market and because it wasn't AMG badged, prices are reasonable. But no one expects a sub-$10,000 car to come with a twin-turbocharged V12 pumping out up to 590 lb-ft of torque from the factory.
8 DeLorean DMC-12
The iconic DeLorean may be the world's most famous movie car thanks to its starring role as a time machine in the Back to the Future franchise but in real life, DeLoreans could barely even hit 88 miles per hour because their stainless steel exterior was heavy and their 2.85-liter Peugeot-Renault-Volvo V6 was severely underpowered.
The owner of one DeLorean just had to have style and performance, though, and upgraded his Buick V6 that he bolted a pair of turbochargers onto. Now, the DeLorean is capable of serious power and low-end torque—meaning it's the ultimate famous sleeper, which is only possible with this exact combination.
7 Ford Ka
The Ford Ka is a tiny subcompact that proved simply too small to sell on the domestic market. But abroad, the Ka is a popular city car—though it's definitely not renowned for being anything close to a performance vehicle. Some insane genius, though, realized that the Ka was, therefore, the perfect candidate for a sleeper build. And boy, did they go all out.
This Ka is now powered by a screaming Cosworth engine and it was even converted to rear-wheel drive from its factory front-wheel-drive layout. The combination of super light weight, high-revving engine, and totally unassuming looks makes this Ka a sleeper that can take just about anyone by surprise.
6 Volvo 242
Volvos from the 1970s and 80s are lovingly referred to as 'bricks' by their owners. From the coupe to the sedan and the station wagon, their simple styling complements rugged mechanicals that make these perfect driver cars, even today.
There's also a sizable community that loves pumping their bricks up into serious sleepers, as is the case with this LS-swapped 1982 Volvo 242 coupe. The LS3 V8 fits under that long hood with plenty of room, and this car's layout comes from an era before Volvo switched to mainly using front wheel drive. Even with a little tinting and darker wheels, no one expects a Volvo to crank out this kind of power.
5 Volvo 240 Wagon
Volvos feature heavily on this list because they're thought of so consistently as boring cars. The 'brick' moniker applies extra to mid-1980s Volvo station wagons like this 240, which happens to be a very serious sleeper build beneath that beige exterior. Under the hood lurks a Toyota 1UZ V8 paired to a Garrett GT4088 turbo running around 14 PSI of boost.
That's just in reliable form, though, and the owner has run this 240 at 16 PSI, as well. At that point, the wagon was dyno-tested and put out 500 horsepower at the rear wheels. If those tires can handle that much oomph, there's a good chance this mommy wagon could do a sub-4 second 0-60 run.
4 Honda Odyssey
When Honda released the first-gen Odyssey on United States soil, the reaction was immediately muted—just like the vehicle, itself. Instead of the industry standardized sliding doors, Honda had gone back in time to use four normal doors, and the car's hand-held vacuum looks didn't help.
But this Odyssey hides a secret that's earned it the nickname 'Rowdyssey' thanks to a 700 horsepower drivetrain under the short hood. That kind of power in such limited quarters can only come via serious boost—in this case, up to 30 PSI from a single turbo. Burning out from the elementary school parking lot never looked so boring.
3 Honda Odyssey
This Honda Odyssey barely qualifies as a sleeper. The problem it faces mostly has to do with its stance and a plethora of rear window stickers (that don't feature the driver's stick-figure family, for some reason). That roof cargo box and the fact that it's an Odyssey save the day, though, and that's good for the gearheads out there because this sleeper is one for the record books.
The project began with the stated goal of keeping everything as close to "stock" as possible, and somehow this Odyssey is cranking out north of 1,200 horsepower on its original block. The engine was rebuilt, obviously, and also features a Turbonetics BTX7265 turbo, an RG45 wastegate, and a Godzilla blow-off-valve—plus, a legit six-speed sourced from an Acura TL.
2 Saab 9-2X
If something looks familiar about this Saab station wagon, that's because winter is coming and there are few cars that snowboarders love to charge up the hill with more than a Subaru WRX or STI. Check out the 'SAABARU' license plate—a reminder that the Saab 9-2X was essentially a rebadged Subaru that shared parts with both the WRX and its STI big brother, with slightly less aggressive styling and a bit more luxury on the interior.
Of course, that subdued design makes any 9-2X a great candidate for a sleeper build. Throw on a big turbo, a Cobb Accessport tuner, and you're good to go shred the gnar and any wannabe slow-pokes scared of a little snow on the way to the mountain.
1 Mercury Comet
This Mercury Comet earns style points for its patina, red interior, and overall design but just about zero percent of the driving population would expect it to be fully hot-rodded. In fact, the exterior looks exactly how its owner desires—and the mechanicals are done up to perfection, as well.
It has a 350ci Chevy V8 from a pickup truck under that long hood, plus a Corvette floor-shifter sending power to the rear wheels. It may not seem like it's ready for a day doing burnouts from stoplights and embarrassing owners of brand new Mustangs but that's why they call them sleepers.
Sources: Engine Swap Depot, Speedhunters, and Daily Turismo.