A bulging hood is the biggest giveaway that you're not looking at an ordinary Cadillac CTS, but the super-quick 2012 CTS-V sedan. It has a supercharged engine that's so big it can't fit under the ordinary hood

2012 Cadillac CTS-V Sedan

What was tested?

2012 Cadillac CTS-V ($63,215). Options: Premium paint ($995), 19-inch satin graphite wheels ($800), wood trim package ($600), yellow brake calipers ($595), Recaro performance seats ($3,400), sueded trim ($300). Price as tested (including $875 destination charge and $2,600 gas guzzler tax): $73,380.

Why buy it?

If you want the fastest four-door car in the world, this is it. It's designed for the racetrack but is comfortable enough to use for ordinary driving - an American engineering masterpiece.

Why avoid it?

It burns through gas like crazy, enough to qualify for the gas-guzzler tax. Its brakes feel a lot better at high speeds than they do around town.

If you want to buy the fastest four-door car in the world, where do you look? You might think of something Italian, like a four-door Ferrari or the Maserati Quattroporte. Germany is another obvious place to consider, with the Porsche Panamera, BMW M5 and Mercedes-Benz AMG models generating lots of headlines.

But you'd be wrong.

The fastest production sedan in the world is actually made here in America, and it's called the Cadillac CTS-V. This car takes the smallest Cadillac sedan and soaks it in horse steroids, adding a 6.2-liter engine, ridiculously huge brakes and an advanced suspension to create the most exciting car I've ever driven with a baby seat strapped in back. And yes, the baby loved it.

This is the heart of the 2012 Cadillac CTS-V, a 6.2-liter supercharged V8 that makes 556 horsepower. It's hard to believe Cadillac could cram it into the small CTS engine bay.

2012 Cadillac CTS-V 6.2-liter supercharged V8

At its core, the CTS-V is all about power. It makes 556 horsepower from a supercharged Corvette engine - the kind of number normally associated more with Italian supercars than with Grandma's favorite brand - and it sounds phenomenal while making them. Everywhere you go, it feels like you're driving an executioner. This is a car that always wants to kill someone, so sinister is its demeanor and snarling exhaust note.

One of the most surprising things about this car is just how drivable it is, though. It's obviously engineered more for the racetrack than anything you can do legally on public roads. Heck, it recently set track records on Germany's historic Nurburgring circuit, which is nicknamed "the green hell" for its 154 turns that are torture on racing drivers. Yet you can drive the CTS-V on the highway in near silence while cool air chills your backside in the ventilated leather seats and soothing music plays over the satellite radio. It's absolutely remarkable.

One of the big reasons for that dual personality is the magnetic suspension system that was inherited from the Corvette. In its normal "touring" mode, the suspension is relatively soft and supple - firmer than the ordinary CTS, but not what you would want on the racetrack. Press a button, though, and the suspension's "sport" mode makes the suspension rock hard. It all but eliminates body roll in high-speed corners and is like installing a full track-day suspension in an instant.

The engineering that went into this car blows me away. It can accelerate from zero to 60 mph in just 3.9 seconds, a figure that is better than all but a few, hyper-expensive exotic supercars. And the only car I've driven with a similar dual-nature personality - full-on racetrack thrills while also being comfortable enough for ordinary grocery trips - is the Audi R8, which is based on a Lamborghini design.

The R8 costs $114,000 and makes 430 horsepower. The CTS-V costs around $63,000, makes 556 horses and comes with a back seat. You do the math.

Like any race-bred car, the CTS-V has its downsides. It's rated for 12 miles per gallon in town and will get even worse than that when driven aggressively, so you practically need an oil tanker to follow you around on the street. And because its brakes are designed to work beautifully at triple-digit speeds, they don't feel as good at lower street-legal speeds. You really have to mash the pedal hard to stop from low speeds when the brakes are cold.

That's a small price to pay, though, for driving the fastest sedan in the world. The CTS-V performs like the most expensive, rare and exotic cars on Planet Earth, yet it costs a fraction of what they do and is built in Lansing, Mich. Americans everywhere should be proud.