A "sleeper" is any car that looks "ordinary" but has far more power than cars of similar ilk.
The "method" to build a sleeper has changed somewhat here in the USA. In my hot-rodding days everyone swapped in a V8. Nowadays import cars are more loved and a lot of engine work goes into those as well, plus nitrous, turbochargers, and so on. I'm "old school" but also an "old fart".
For most of the 90's you'd have caught me driving a 1975 Dodge D200 extended cab, painted in Kenworth Red. Even though my fabricated 4-link rear, DOT-legal street slicks, and wheelie bars were *obvious*, most of the street car guys I'd join on occasion would take a gander and simply shrug the truck off as "neat looking but it's a truck".
When I'd launch and spank all of them most of the time things changed. I built the truck with a 451 "B" block stroker, custom EFI using GM components (with a Syclone/Typhoon ECM with custom code - developed over two years and tweaked thereafter), a pair of T4-sized Garrett turbochargers, and lots of custom fabrication. This truck had the street manners of a *****cat until you romped the throttle - so it was my daily driver AND my toy. In building that truck I violated a lot of the "normally applied rules" whereas I ran a silly-low compression ration (7:1) and yes, I had turbo lag for sure because of that and the size of the turbochargers, but that was okay because while a race can be won off the line if the run is long enough having crazy boost (30+) very quickly makes up for it. So all the import guys would pull ahead upon seeing the flag then I'd catch them fairly quickly, and blow right by, with much more power/boost available - all in a 5500lb pickup truck. Here's the kicker - even with the bigger engine, turbochargers and the like, I averaged 17 mpg on the highway as compared to it's original carb-induced 318 cid's mileage of 8.5 mpg average highway. Of course I couldn't get that mileage with the boost screaming, which often it was.
A close friend of mine has what I consider to be one of the coolest sleepers out there - it's a 1992 or 1993 Ford Taurus, and other than it's noticable rake and much wider rear tires (and slightly flared body to cover), it looks fairly ordinary. The interior is leather and is stock, except for the full cage. Even with this changes, you can't help but say to yourself "Darn, it's just a taurus", and that was the idea.
The suspension was hand-fabricated - unequal length a-arms front and back, tweaked and tuned to professional levels. The engine is an all-aluminum Rover V8, including the accessories - the engine/acc weigh about 320 lbs in entirety - the transmission is a 6-sp manual and was built to be as bulletproof as possible. Oh, did I mention the pair of large turbos and custom EFI? It's a mean machine and my friend spent about six years building it - and the craftsmanship and performance shows that labor well. Like my truck, it behaved well enough to drive on the street as a daily driver but rocked the streets and the strip when he had an opportunity to do either. Like Kenny mentioned a RWD Civic using a vette transaxle "out back", my friend did the same thing using similar components. The car has no useful storage space except the glove-box, but it's not the car to take on a long trip with the wife and kids.
As my F350 crewcab ages, I've slowly built (as time and dollars allow) a 500cid twin-turbo stroker much along the ilk of other projects, and once again will have another toy.
Even though I'm "old skool" enough to believe that V8's belong in everything, I'm not so close minded that I can utilize a lot of the ideas the newer breed of hot-rodders embrace - particularly forced induction.
It's really cool to combine - and make even more power. Of course as states increase points and fines and quantity of officers, the days of enjoying such power on the street becomes less and less likely and less enjoyable considering the consequences. Here in NJ we have a lot of "safe corriders" which is just a barely signed patch of road that gives you double fines, double points.
I enjoy building things, so even if I can't scream something on the roadway the same way I used to, I still enjoy starting with a generic POS and turning it into something wild and crazy - even though it will still look like a generic POS when I'm done
I used to do these kinds of modifications to old wagoons - Falcons, LTDs, etc for a while. Before that I had a "topless land yacht" fetish - big engines in giant land cruisers - my favorite being a 1969 Ford XL Convertible. I miss one finger driving.
