We all love the idea of an underdog, the scrappy, unassuming bruiser who can bloody the heavyweight champ’s nose or even walk away with the belt. I’m not entirely sure that’s a purely American trait either, no matter how many times you wave Rocky or Die Hard or Predator in front of my face. Supporting the up-and-comer is more of a general human trait, as indicated by the plethora of factory built hot rods that come out of Europe and Japan: 600 HP Audi wagons that look like normal family haulers, or discrete rally-inspired sport compacts with turbocharged power plants.

It makes sense; it was the British who first used the term "Q-ship" to describe a car with far more performance than its exterior appearance would suggest. That term originated from WW1 and WW2, when the world's Navies would outfit benign-looking merchant ships with armor and an assortment of hidden heavy weaponry, and then send them out lure and destroy enemy submarines. That fits the ethos of a sleeper to a T: every enthusiast loves the idea of a subtle commuter with enough power to blast holes in the ego of every Ferrari driver within a 50-mile radius. That sense of satisfaction is only magnified when you build the car itself, as the following list attests.

20 Volkswagen Type 2

via engineswapdepot.com

There aren’t many cars more iconic than the Volkswagen Type 2: a symbol of the 1960s peace and love movement, a friendly looking box that somehow looked happy to see you, especially when covered in pastel paint jobs and driven by hippies with flower-braided hair. That lack of aggression also bled into how the car drove, as buyers were suck with a selection of rear-mounted, air-cooled boxer-four engines that struggled to push the Type 2’s boxy frame past the heady reaches of 60 MPH.

For former professional motorcycle racer Fred Bernhard, that would simply not do. His so-called "Race-Taxi" rose to internet superstardom back in 2007, when a video surfaced of him and his modified Type 2 outrunning Porsches and Aston Martins around Belgium’s Spa circuit. As you may have gathered then, this van is pretty far from stock. In fact, there isn’t much Type 2 left under the Race Taxi at all. The car’s powertrain and chassis has essentially been lifted wholesale from Porsche 993 Turbo, with the Kombi body slightly widened to fit over it. It doesn’t show too much from the outside. Even with the one-piece carbon fiber roof, racing livery composed of vintage VW factory hues, magnesium-center BBS wheels, and Pirelli P ZERO racing slicks, you might still confuse it with a particularly well-executed show car at first glance.

19 Ford Escort

via youtube.com

When you think of the words “Ford Escort” and “Cosworth”, the first thing your mind brings up is probably the run of factory-built, wildly winged AWD rally beasts. For the unaware, the imaginatively-named Escort Cosworth, with its near-indestructible YBT turbocharged inline-4, was meant for both Group A rallying as well as road-going homologation. Crazy as that car was, this Cosworth-powered Escort takes things even further. The work of Düsseldorf-based passionford.com user Cyril Sneer, this project has been executed with typical German efficiency and engineering rigor.

Combining the shell of a third-generation Escort, the running gear of a Ford Sierra Cosworth (the mechanically-related predecessor to the factory Escort Cosworth), and the floorpan of an AWD Sierra, along with a heap of custom-fabricated parts to get everything to fit together, a drag-strip terror was formed.

In no small part thanks to a Garrett GTX3076 turbocharger, that Sierra’s YBG four-cylinder now kicks out somewhere in the region of 500 HP, a more than healthy increase over the stock 220 HP. That motor is hooked up to a straight-cut gearbox channeling power through all four wheels, with the build being completed with competition-ready accessories like a trunk-mounted fuel cell and fully caged interior.

18 Ford Granada

via flatout.com.br

Alright, while I’m sure a fairly aggressive-looking family sedan doesn’t merit the label of “sleeper” quite as much as some of the other entries on this list, I still thin you’ll be more than surprised to find out what lurks beneath the hood. Build by Norwegian mad genius/Ford obsessive Joel Olsen, this monster, dubbed “ZZZ ZZZ”, is the result of 17 years of hard work.

After our Scandanavian friend originally bought the car, he ripped out its tepid power plant and replaced it with a Cosworth-tuned inline-four good for 600 HP and a 200 MPH top speed.

Most people would stop at that, and that’s a perfectly right and sensible point of view: a competition-spec motor hand-delivered by the god-kings of internal combustion fettling. Well, that wasn’t enough for Mr. Olsen (funnily enough, that basically summaries this entire build). Most of the chassis is entirely custom-fabricated, with a pushrod suspension setup, Cobra Mustang rear end, and drilled brake rotors from Porsche. It’s the engine that’s the crown jewel of this build though, a twin-turbo 4.7-liter V8 similar to the one in the back of the Koenigsegg CCR. While the Swedish hypercar made 806 HP, the Grenada’s unit features custom-fabricated, bleeding-edge race tech like beryllium-copper valve seats and 300M steel conrods. On pump gas, it makes 1,300 HP. Olsen figures it’ll easily crack to 2,000 HP mark once it’s fully dialed in.

17 Ford Focus Mk1

via bringatrailer.com

If you discount the Ken Block wannabes wrapping their sparkling new Focus RS models around a tree because they assumed "drift mode" would turn them into driving gods, Ford’s compact car has never really offered many opportunities from the factory for a bit of sideways shenanigans. That’s a shame, as a slippery, lightweight car with a manual transmission is, in my opinion, a definitive path towards peace on Earth. Perhaps it was this deep-seated sense of moral obligation that persuaded aftermarket garage Kugel Street Rod Components to start a service that converts first-generation Focuses (made from 1998 to 2005) into tail-happy lunatics using Ford factory components.

The company offers two choices of Ford V8 crate engine in either 4.6 liter or 5.0 liter flavor. According to bringatrailer.com, this example runs a 5.0 liter from a Fox Body Mustang, which comes with a host of go-fast goodies, including ported and polished Thumper cylinder heads, roller rockers and a performance camshaft. That muscle is channeled through a rebuilt World Class T5 5-speed transmission. Altogether, it makes for an extremely convincing sleeper; its clear the previous owner gave this serious thought, as the Focus retains its single weedy downturned exhaust pipe, an effect that is only slightly spoiled by the honking great differential and wide rear tires.

16 Kia Sorento

via facebook.com

When you think of fast Kias, I imagine that the Stinger is the first thing to cross your mind, and with good reason: a twin-turbocharged fastback luxury sedan isn’t a car that you would associate with the company even two of three years ago. Of course, it serves as a perfect illustration of how fast the company has changed. If you needed to go fast in a RWD Kia from the mid 2000s, you couldn’t just go to the dealership. You’d have to get creative. Like, really creative. Creative like Craig Gibson.

After the 3.8 liter Lambda V6 engine in his 2007 Kia Sorrento blew itself to smithereens, Gibson saw the opportunity to do something equal parts awesome and hilarious.

Being something of an amateur mechanic (that might be understatement of the year, considering the difficulty of this swap), he junked the stock motor and somehow wedged an iron block LY6 V8 engine (sourced from a 2009 Chevrolet Silverado 2500 HD) under the hood. He proceeded to give a bit more juice by installing LS2 headers from a Pontiac GTO, a GMPP LS3 intake manifold and fuel rails and injectors, as well as a 90mm throttle body. Gibson’s only clue as to what’s under the hood are custom ‘LSX-powered Sorrento’ badges on the SUV’s flanks.

15 Audi S4

via youtube.com

Audi’s performance wagons have been a huge source of automotive envy from North American enthusiasts. There are few companies that can consistently deliver cars with such a beguiling mix of subtle looks and kidney-pulverizing acceleration, but Audi has a spotless record in this segment, tracing its roots from the 311 HP Audi RS2 from 1994, which could out-accelerate a McLaren F1 (to 30 MPH at least, but still), all the way to the most recent B9-chassis Audi RS4, which teams a twin-turbocharged 2.9 liter V6 to a quick-shifting eight speed automatic transmission and rear-biased AWD system for a 0-60 run of just over 4 seconds.

Now, in stock form, the B5-chassis Audi S4 does nothing to disgrace that illustrious heritage: a 261 HP twin-turbocharged punch inside hidden inside the car of a well-paid intern. This modified example just takes that theme and runs very fast and very far with it. Instead of the stock 2.7 liter mill, the foundation on which this build rests actually comes from a B5-chassis RS4, which used a larger 3.0 liter unit. That motor has been fitted with a plethora of big-power upgrades, including a pair of Garrett GT-3086 turbochargers, which come together to crank out a ridiculous 1,200 HP. Aside from the exposed intercooler piping lurking behind the front bumper, aggressive-looking tyre compound, and fixed-back Recaro racing seats, there isn’t anything immediately visible to indicate that this S4 could turn in a 188 MPH run at the Vmax200, the UK’s most famous runway top speed event.

14 Toyota Camry

via autoblog.com

Toyota’s “Grounded to the Ground” advertising campaign for the 2012 Camry has been mocked endlessly on enthusiast forums, and I’m not going to say its unwarranted. No one with more than half an ounce of automotive knowledge is going to recognize the XV50 as a masterpiece of driving dynamics, and that’s just fine. Not every car needs to be a knife-edged track rat with the ride quality of a nail-studded ironing board.

Not wanting to be forever known as the flag-bearer for all-things beige though, Toyota tried to shake off the Camry’s airport taxi reputation in spectacular fashion at the 2014 SEMA (Specialty Equipment Market Association) show in Las Vegas.

Essentially a paradise for modified car lovers, the SEMA show allows aftermarket companies to flex their full engineering might while allowing automakers to let their hair down with some wild and wacky one-off creations. For instance, stuff like this, built by Toyota’s Motorsports Technical Center. Dubbed the ‘Toyota Sleeper Camry’, this unassuming family sedan hides a power to weight ratio closer to a cruise missile than a mid-sized commuter. The car’s body is actually hinged at the rear, allowing its builders to lift it up and expose the tube-framed insanity underneath. There’s no Camry here, not really. At the front sits a Tundra-sourced 5.7 liter V8, equipped with a supercharger and a wet-shot nitrous system. That package is good for 850 HP and a 9.8 second quarter mile pass.

13 Honda Odyssey

via youtube.com

Built by Youtube automotive channel and Honda fanatics BoostedBoiz, this family hauler holds a nasty surprise for any would-be stoplight drag racers. From stock, the RA1-5 Odyssey wasn’t much of a speed demon. Buyers were stuck with a dinky 2.2 liter F22B6 inline-four, good for just over 130 HP. That’s fine and dandy in a Civic or even an Accord, but a minivan has a lot more mass to haul around. I suppose that’s why BoostedBoiz found it to be the perfect starting platform for a monstrously powerful sleeper: no one would suspect a thing. Out went the F22B6, and in went another 2.2 liter engine, this time a VTEC-equipped H22 from a Honda Prelude. This is where things get very spicy indeed: while the engine retains a stock head, the rest of the motor has been built up with a laundry list of budget-friendly upgrades, including Supertech springs and retainers, eBay H-beam rods, Arias pistons, eBay 2200cc fuel injectors, and an eBay GTX3582R turbocharger. Even with its stock open differential, this forced induction Odyssey managed to marshal its 727 HP for a 153.21 MPH trap speed through the half-mile.

12 Mazda MPV

A Black Mazda MPV
via speedhunters.com

Let’s examine another Japanese family hauler build, this time a 1993 Mazda MPV with some serious one-off fabrication work. In stock form, I actually think the MPV would be kind of fun to hustle around; with a front-engine, rear-wheel-drive layout and longitudinally-mounted 150 HP 3.0 liter JE V6 sitting inside its stubby little nose, it probably wasn’t very fast, but at least it was more skid-friendly than most of today’s FWD and AWD crossovers.

Well, for former Speedhunters contributor David Swenson, that wasn’t good enough. His MPV, modified with the help of his father, packs a 388 HP punch courtesy of a lightly massaged VG30DETT from a Nissan 300ZX.

In order to get the chunky twin-turbocharged V6 to fit in the cramped recesses of the Mazda’s engine bay, a few of the MPV’s quirks had to be sacrificed, such as the column mounted shifter (replaced with a Nissan-sourced floor shifter). Surprisingly, the VG30DETT was able to use the same mounting points as the original JE. For maximum sleeper potential, the van’s exterior was left completely untouched, giving no clue as to what resides underneath.

11 Volvo 245

via sucksqueezebangblow.com

What happens when you combine Swedish tank-like goodness and Japan’s most indestructible inline-six? The most reliable modified car ever built, I suppose. This natural melding of motor and machine comes from the mind of Swedish 2JZ whiz Peter Björck, who’s also known for his damn-near 1,300 HP Supra that was featured on Speedhunters. While the 2JZ in Björck’s 245 hasn’t had the sheer amount of effort poured into it as the one in his JZA80, it hasn’t been left alone either.

In order to handle some additional boost, some engine internals were replaced with sturdier items, such as Eagle connecting rods and ARP head studs. That additional boost is provided by a single massive KKK29 snail, instead of the factory setup that used two turbos. The rest of then engine mod list includes some high-end components like Bosch 2200cc injectors, a Walbro fuel pump, and a PRC wastegate. Power is sent to the rear wheels via a BMW M5-sourced rear differential. Other than a set of R-Sport shocks with basic lowering springs that drop the car to well below its factory ride height, there’s not much here to tell onlookers what’s going on. That sleeper status is only reinforced by details like the steel wheels, roof-rack, and stuffed dog looking out the rear window.

10 Honda Civic

via roadandtrack.com

There’s no shortage of high-flauntin' modified civics on the internet; stripped and caged track rats with ironing boards for rear spoilers and front splitters massive enough to double as snow plows, or drag strip specialists with oil drum front slicks and drilled bumpers. Despite that seemingly endless well of purposeful-looking machinery, there seems to be a dearth of Civics modified with subtle performance in mind. I’m fine with that, as it makes those unique builds like this 2014 Civic Si stand out even more.

This sleeper, as featured by Matt Farah from The Smoking Tire, started life with a naturally aspirated K24Z7 inline-four, good for 205 free-revving horses, before its power-hungry owner foisted a metaphorical ton of upgrades upon it.

The laundry list of mods includes a MAKSPEED turbo kit, Wiseco pistons, Manley conrods, and ARP head studs. That’s good for 450 HP delivered to the front wheels, more than enough power to catch the unaware off guard, so it’s a good thing that Honda fitted a helical limited slip differential as a standard option. The only concessions to this sport compact’s performance potential that are visible from the exterior are an array of meters and gauges, nearly hidden by the A-pillar.

9 Buick Roadmaster

via bangshift.com

The Roadmaster. That name harkened back to the glory days of GM’s Buick brand, when they were more than just away from the conglomerate to sell cars in the image-conscious Chinese automotive market. Throughout much of the mid-20th century, the badge stood for art-deco masterpieces designed by the man himself, Harley Earl, an automotive artiste by any other name. So when GM revived the name after a 33-year hiatus for a sedate-looking family hauler that looked purpose built to star in the background of retirement home ads, people may have been a little bit mad.

However, styling didn’t matter, not when you had an LT1 engine on the options list. For those wondering why this is a good thing, the LT1 was also used in the Chevrolet Corvette C4, as well as the Camaro Z28 and Impala SS, and was good for 300 HP and 340 lb ft of torque. Unfortunately, unlike those cars, the Roadmaster was saddled with a dim-witted 4-speed slush-box. This Roadmaster, featured on Regular Car Reviews, attempts to rectify that problem via the crude installation of a T56 manual transmission and a few other choice parts sourced from a Camaro, hence the portmanteau nickname of "Cammaster."

8 Ford Flex

via wheelwell.com

With the recent news that Ford would be discontinuing all of its cars (aside from one Focus trim level and the Mustang) in favor of a model lineup composed entirely of crossovers, I couldn’t help but wonder if the Flex would have made the cut. After all, it occupied a weird spot in the market, a sort of proto-crossover that incorporated lots of vintage station wagon styling cues to disguise a surprisingly massive frame; after all, it was technically classified as a full-size SUV by the EPA. I’m not really sure where I’m going with this, other than a fact that it was a refreshing piece of design in what is today a very crowded market.

It also had the makings of a fantastic sleeper: Ford offered the 3.5 liter Ecoboost V6 as an engine option, which made a very healthy 355 HP. There’s a pretty large aftermarket for these engines now, and cars like Brent Long’s 2013 Flex do a good job of illustrating their potential.

Among the list of power upgrades are an MDesign Carbon intake, a SCT X4 tuner, and a Devil's Own Stage 2 methanol injection kit. Even with that relatively small list of mods, Long’s Flex makes 500 HP and 550lb ft of torque. Mods visible from the outside were kept relatively light, and only serve to enhance the function of the car: a Power Stop Z23 brake package, Megan Racing EZII adjustable coilover suspension, and 275/40 Nexen N'Fera RU5 Sport tires.

7 Plymouth Voyager

via bangshift.com

The second-generation Plymouth Voyager would be on of the first cars we’d recognize as a minivan as the term is defined today. Along with its platform mate, the Dodge Caravan, it set the standard for the breed and almost singlehandedly established the that category of vehicle as being one of the most ubiquitous modes of family transport in the world. Unlike their vaguely agricultural ancestors, which used heavy duty ladder frames, the Voyager and Caravan were built on Chrysler’s more civilized S platform, itself a derivative of the ubiquitous K-car platform.

The K-car chassis’ age and seemingly endless parts supply actually mean that they have the makings of pretty potent sleepers: check out this mint, unassuming build for proof. The engine is a 2.5 liter short block fortified with a host of aftermarket upgrades, including a Turbonetics turbo kit, a Treadstone TRV1859 720hp intercooler, a Turbos Unleashed ported exhaust manifold, and a 52 mm throttle body. Hooked up to an A523 transmission with a Stage III ceramic clutch, rebuilt Mopar axles and Michelin Defender tires, the entire package is good for a 13.8 second quarter mile run at 101 MPH.

6 BMW 130i

via autoevolution.com

Many consider BMW’s 5.0 liter S85 V10 to be the finest motor the automaker has ever built for road use. That’s high praise, especially considering the company’s back catalogue. It was used for just five short years in the BMW M5 E60 and M6 E63, a high-revving naturally aspirated jewel of an engine that sounded like a vintage F1 car gone completely off its meds, and thus completely incongruous when crammed inside the body shell of a relatively sedate pair of luxury cars.

During a road test on Top Gear back in 2006, Jeremy Clarkson called the E60 one of the finest cars he’s ever driven, having managed o disregard the infotainment system's foibles and tricky six-speed sequential gearbox.

I suppose that the German owner of this formerly straight-six powered BMW 130i wanted to up the incongruity factor by wedging this motorsport-inspired masterpiece into one of the smallest cars BMW builds. Now, aside from the gorgeous BBS wheels and hard-edged 8,250 RPM shriek from the storm drain exhaust tips, there’s not a whole lot of clues as to what’s actually going on here.

5 Lexus GS 300

via motor1.com

To me, its always seemed as though the Lexus GS was the unloved middle child in the brand’s RWD lineup, forever overshadowed by its more exciting IS younger brother, and less luxurious than the LS flagship. I guess you could say that’s exactly where the GS should be positioned in the Lexus lineup, but its hardly a recipe for attracting a massive audience.

However, first and second-generation cars to hold a valuable prize for enthusiast looking to tool around in something quick and inconspicuous: overseas buyers could opt for a twin-turbocharged 2JZ-GTE straight-six, same as the venerable Supra JZA80, without having to pay that car’s ridiculous Fast and the Furious tax. Of course, North American buyers were left out in the cold in this regard, being stuck with the naturally aspirated 225 HP 2JZ-GE straight-six instead. Still, swaps were far from the hardest thing in the world. It seems that the owner and builder of this modified second-generation GS agrees. Under the hood of this librarian-spec example lies an extensively modified 3.0 liter 2JZ-GTE, apparently good for a blistering 1,300 HP when running on ethanol. Transmission is a General Motors TH 350, hooked up to a TRD 3.76 differential.

4 Toyota Corona Mark II

via engineswapdepot.com

We’ll do another RWD Toyota sedan, this one being a far less powerful a and a hell of a lot more exotic. This X30-chassis Corona Mark II (sold in North America under the Cressida name) is owned by New Zealander Nathan Messenger. From stock, these elegant RWD sedans came equipped with a variety of relatively tepid inline-fours and sixes. Messenger is no stranger to the swapping them out however; his first X30 project ended up with a 1UZ-FE V8 and W-series manual transmission. Shifting financial circumstances forced him to sell that all-Japanese hot rod, but he soon got another opportunity in the form of a JDM-spec Corona Mark II.

While he initially planned to revisit his Japanese V8 theme, his wife surprised him with an incredibly rare 5.0 liter Toyota 1GZ-FE V12 as a 10th wedding anniversary gift, plucked straight from the nose of Toyota’s JDM flagship, the Century.

With the 1GZ being slightly taller, longer, but narrower than the V8, fitting it into the Corona’s spacious engine bay wasn’t as hard as it could have been. Messenger then proceeded to fabricate a custom equal-length crossover-style manifold, complete with copper anodized open trumpets to give it a sound unlike any other Toyota sedan on Earth.

3 Rolls Royce Phantom

via youtube.com

While you might scoff at the idea of a $400,000 car being considered a sleeper, give it a bit of thought: I mean, Rolls-Royces are hardly known for their straight-line antics or razor-sharp handling. No, all of that money goes towards making sure the driver is as isolated as possible from the imperfections of the daily commute. The seventh generation Phantom, introduced in 2003, was the first car to bear the name following BMW’s buyout of the automaker. Its BMW-developed 6.75 liter V12 engine focused more on buttery-smooth power delivery rather than all-out performance, hence its under-stressed output of 453 HP. Count on Japan to turn that philosophy on its head, and turn this British limousine into something far weirder.

After the V12 engine in this 2008 Phantom crapped out at just 119,000 miles, its owner, not wanting to wait another two years for a replacement, opted to solve the problem himself. In crazy-person-speak, that translates to “put a 2JZ in it.” Which is exactly what our intrepid Japanese hero did, and in spectacular fashion I should mention: the 2JZ-GTE in his Phantom is twin-charged, combining a Trust T78 turbo with an HKS GT8555 supercharger kit. With the boost cranked up to 30 PSI, along with a host of high-performance upgrades, like HKS forged pistons and a GReddy exhaust manifold, this weirdo is good for 900 HP.

2 Volkswagen Caddy

via engineswapdepot.com

The Volkswagen Caddy is a car that is probably unfamiliar to the North American consumers. There isn’t really much to it though; its essentially a light-duty utility vehicle made from a hodgepodge of VW group components. This face lifted third-generation van uses a Golf Mk5 front suspension, with much of the remaining underpinnings coming off a VW Touran, a European-market family hauler.

While most Caddy vans are powered by soul-draining slow inline-four diesels, the owner of this brilliant blue example, one Stephen Gibbons hailing from the UK, wanted to go just a little bit faster.

He junked the stock motor, and replaced it with a turbocharged 2.0 liter inline four from a Mk7 Volkswagen Golf R. In stock form, that engine, known internally as the EA888, cranks out 306 HP. Not good enough for Gibbons, who removed the stock IHI turbocharger and fitted a REVO IS38ETR snail in its stead, along with a Stage 3 tune meant for 97 RON fuel. Power is sent to all four wheels via a Haldex AWD system, also sourced from a Golf R. That list of parts is good enough for a 500+ HP output and 11.12 second quarter mile run.

1 Volkswagen Golf Mk1

via speedhunters.com

We’ll keep that Volkswagen ball rolling and head back in time, this car being another melding of parts from across the vast reaches of Volkswagen Group’s enormous empire; this Mk1 Golf is a seriously unique vehicle, having most of its original guts pulled out and replaced with components from Stuttgart’s finest sports car builders. OK fine, back in the seventies, VW didn’t actually hold a controlling stake in Porsche, but my point still sort of stands.

This build was executed by Hanover, Germany-based tuner Nordstadt, and wrapped a lightly massaged Volkswagen Golf /Rabbit/ what-have-you shell around the underpinnings of a Porsche 928. Obviously, the latter car was much bigger than the car it was donating its innards to, so Nordstadt shortened the Porsche’s chassis to fit. The build didn’t stop there however, as this dinky little commuter packs the 928’s stock 4.5 liter V8 under its stubby hood. That relatively massive unit was good for 219 HP. In a German grand-tourer, that’s a recipe for sluggishness. In a car almost half a ton lighter, well, let's just say things were probably a lot more interesting.

Sources: speedhunters.com, engineswapdepot.com, bangshift.com