Remember back 20 years when Mercedes and BMW scoffed at the idea of a Japanese luxury competitor? They weren't alone; basically everyone did. Well, we guarantee those companies are doing anything but scoffing now. This time around, with Lexus going after the Germans' most profitable niche - hottie factory tuners - those old hands and relative newcomer Audi are doing everything but scoffing. We bet they're wishing they've been doing what we've been up to for the past week. That is, driving the holy hell out of a Lexus IS-F prototype to gauge the threat. Well friends, we know the answer, while M, AMG and Audi's RS are (for now) left guessing. But first, let's look at what makes an IS-F more than a just an average IS, starting with what's under the hood.

Pull back the engine cover and you're looking at Darth Vader's chest plate, an expansive jumble of wires, black boxes and even more wires. Despite all that, or perhaps because of it, the IS-F gets ultra-low-emissions vehicle (ULEV) status, and won't be slapped with a gas-guzzler penalty. Dig deeper beneath that electrical matrix, and there beats the heart of a brute. It's a 5.0-liter V8 dubbed 2UR-GSE, related to the 4.6-liter 1UR-FSE found in both the GS and the LS. According to company figures, this bored out, free-breathing version of the Lexus family eight-banger puts out 416 gnarly horsepower at 6,600 rpm and cranks out a mighty 371 ft-lb of torque at a fairly lofty 5,200 rpm (though 80% is available at 2,000 rpm).

It's Japanese whiz-bangery to the extreme. Each cylinder gets two fuel injectors, one in the port and one directly in the chamber. The chamber injector is used most of the time, facilitating direct injection, while the low-pressure port injector helps with start-ups in cold weather and to heighten fuel economy under light loads. There's a head scavenge oil pump that ensures lubricant is forced through the engine during hoonatic sideways maneuvers. Likewise, the fuel delivery system uses a similar pump that draws from a sub-tank. There's even a water-cooled oil radiator.

If the IS-F was only a stonkin' engine, we'd have a lot less to talk about. As it is, the car is packed with all sorts of go-faster, hoon-harder kit. Like the eight-speed automatic slushbox that packs a very significant twist. Unlike most other automatics with manual overrides (save dual-clutch setups) there's no stoking the coals and waiting. Activated either by the shift lever or two too-small aluminum paddles, the IS-F's tranny swaps the cogs quickly. Let me restate that. The IS-F's gearbox upshifts in 1/100th of a second. It takes a Ferrari F430 50% longer (150 milliseconds) to accomplish the same task. Yes, this Lexus is capable of upshifting as fast as a 599 GTB. Enjoy banging your passengers' heads on headrests? We've found your sedan. Downshifts are basically as quick, taking 200 milliseconds and are accompanied by an automatic throttle blip to match revs.

Of course, that's in Sport mode. The IS-F actually has three modes. Normal features an especially cruel nanny. Lexus calls this Vehicle Dynamics Integrated Management (VDIM), and it encompasses traction control, stability control, ABS, brake assist, electric brake force distribution, engine torque and the brake-based electronic limited-slip differential that can apply brake and throttle at the same time. In Normal mode, any aggressive movement is interpreted as naughty. As a result the orange idiot light flickers almost constantly. Worse, Normal mode retards the throttle response and overboosts the power steering. Lexus could have just called Normal chill-out mode. Or better yet, Lexus mode.

However, in Sport mode, not only is the throttle response dialed way up and the dual-mode power steering turned down, but if the transmission is left in drive, revs are held right up to redline. Moreover, the VDIM is dialed back to allow for more fun, something engineers call a "higher dynamic threshold," yet enough computer processing takes place to save one's bacon if the IS-F is pushed too far. If you like, you can actually switch everything off leaving only the electronic limited-slip diff and ABS to keep you out of the weeds. But with so much grunt available at all times and a back that's happy to break loose, I found Sport mode the smartest choice.

Brakes are Brembo-supplied and include huge 14.2 inchers up front, 13.6 out back. They're cross-drilled, vented, and even adorned with a Lexus brand. The front calipers contain six pistons of three different sizes. The rears are two-pistoners. The brakes are more than just fade free; they seem to get stronger the harder you stomp them. The suspension is closer to that of stock IS 350 than any other part of the car. Still, the front springs and shocks are 90 percent stiffer while the rear end rates are 50 percent more solid.

Lexus could have used lighter aluminum components and totally reworked the chassis the way BMW's M division does, but they didn't. That said, the IS-F comes in at an acceptable for the class 3,774 lbs. 0-60 takes a factory claimed 4.6 seconds, the quarter mile is over in 13 flat and the top speed is limited to 170 mph. Though, without the governor, the IS-F will do 186 mph. Lexus claims the IS-F was developed on no less than six racetracks, including the Nürburgring, Laguna Seca and Fuji Speedway. Perhaps keeping the suspension relatively stock is how the IS-F will undercut the competition. Lexus wouldn't give us a specific number, but their new wannabe giant-killer will likely zoom out of showrooms for right around $60,000.

Does all this tech, power and purported sportiness come together and form a winning package? We'll see you back here tomorrow.

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The night following our first day with the Lexus IS-F, after our own Wes Siler managed to procure…