WILLOW SPRINGS, Calif. — All it takes is a quick tap to the ignition switch of Chrysler’s high-performance sports sedan, the souped-up 300 SRT8 in new design for 2012, and that deep-throat bleat spewing from twin back pipes speaks to you with the promise of race-car speeds and crisp fun-through-curves maneuvers.

This Generation 2.0 rendition of the 300 SRT8 carries the formidable credentials of a street-legal racer:  A lowered chassis with taut suspension tweaked for performance, massive 20-inch rear wheels wrapped in 255/45ZR20 Goodyear Eagle RSA speed-rated performance tires, big four-piston Brembo-brand brake calipers and a humongous 6.4-liter V8 engine that’s a high-tech rendition of Chrysler’s fabled HEMI plant with hemispheric combustion chambers.

Chrysler casts the car off the rear-wheel-drive (RWD) 300 series of sports touring sedans for the large-car class. For a vehicle that tips scales to more than two tons, the SRT8 300 is impressively fast.

Timed speed runs on the Willow Springs race track in California’s Mojave Desert reveal that it can romp from zero to 60 mph in a time well below five seconds, then rip pass the quarter-mile post in 12 seconds plus change.

The top speed, estimated by Chrysler, is 175 mph.

Special exterior modifications apply to the new performance sedan, such as a revamped front fascia scored with brake-cooling ducts, an oversized air dam and black chrome upper and lower grille surrounds.

Cast low to the ground on those big wheels with sharp-edged lines strafing across an exaggerated hood, the racy 300 SRT8 projects a stub-nosed prow with massive grille and slab-sided flanks but muscular bulges around wheelwells for multi-spoke wheels with optional black-chrome finish.

Six exterior colors mark the 2012 300 SRT8 in Bright Silver, Tungsten, Bright White, Brilliant Black, Ivory and Deep Cherry Red.

The SRT8 300 totes a larger and more powerful yet more fuel-efficient HEMI engine, a dual-mode adaptive damping suspension system with selectable suspension tuning for world-class ride and handling, a new SRT-badged heated steering wheel with paddle shifters for hands-on-the-wheel shifting, plus the option of a premium Harman Kardon audio kit with 900-watt DSP amplifier and 19 speakers.

The SRT8 treatment for Chrysler’s 2012 300 starts with that expanded big-block engine — a 6.4-liter HEMI V8 which kicks out 470 hp at 6000 rpm plus 470 lb-ft of torque at 4300 rpm.

Torque is channeled to the rear wheels through an electronic automatic five-speed transmission (W5A580) teamed with the AutoStick manual shift controller and an electronically modulated torque converter clutch.

The HEMI V8 comes with standard Fuel Saver Technology (FST) technology which enables it to switch seamlessly and transparently to a fuel-saving four-cylinder mode when all of that V8 power is not needed for romping.

Premium 91-octane fuel is recommended for the 300 SRT8 and fuel economy figures rise to 14 mpg for city driving and 23 mpg on the highway.

SRT engineers worked on the SRT8 suspension.

They lowered it by half an inch and tuned it tightly for performance with tailored spring rates and bushings, big anti-sway bars in place plus anti-skid controls via an electronic stability control (ESC) device.

For the new adaptive damping suspension a driver can select a setting — Auto or Sport — to quickly change shock damping and harshness traits.

To rein so many horses, those 20-inch wheels on the 300 SRT8 carry massive disc brakes. Up front, the 14.2-inch rotors team with Brembo four-piston calipers in aluminum housings. Rear ones with 13.8-inch rotors also get Brembo four-piston calipers in aluminum housings. All four discs are linked and controlled through an anti-lock brake system (ABS) with brake assist (BA) and electronic brake-force distribution (EBD) plus a traction control system (TCS).

Measures for passenger safety in the cabin extend from the sturdy safety-cage construction to front seatbelts with pretensioning apparatus, reactive head restraints and the cabin surrounded by hidden air bags — up-front inflators for front seats plus seat-mounted side air bags and one more to shield the driver’s knee, then curtain-style air bags mounted in headliners above side windows for two rows.

Additional safety assets include the enhanced accident response system (EARS), forward collision warning (FCW), blind spot monitoring (BSM), adaptive cruise control (ACC), and a remote keyless entry system with remote starter.

In the cockpit, genuine carbon fiber trim pieces cover the instrument panel, door spears and shifter bezel.

On the dash a new electronic vehicle information center (EVIC) with full-color graphics in a touchscreen display carries pages with timers for 0-60 mph, eighth-mile and quarter-mile, 60-0 braking distance, plus lateral and longitudinal g-force measurements.

The front seats with active head rests are heated and ventilated, while the rear seats also are heated.

An optional Premium Leather Interior Package adds Poltrona Frau leather-wrapped upper door trim panels, instrument panel, cluster brow and center console side panels with Nappa leather covering door bolsters and armrests and the center console armrest.

Chrysler constructs a more powerful and more sophisticated 2012 300 SRT8 priced from $47,180.

2012 CHRYSLER 300 SRT8 SEDAN SPECIFICATIONS

• Description: Full-size performance sedan
• Model options: 300 SRT8
• Wheelbase: 120.2 inches
• Overall length: 200.3 inches
• Engine size: OHV  6.4-L V8/HEMI
• Transmissions/speeds: Auto/5/AutoStick/W5A580
• Rear/front drive: Rear
• Steering: Power rack and pinion
• Braking: Power 4-disc, Brembo 4-piston calipers, ABS/BA/EBA/TCS/ESC/BSM/EARS
• Air bags: 2 (front), 2 (side), 1 (driver knee), 4 (side curtain)
• EPA mileage est. city/hwy.: 14/23 mpg
• MSRP, est.: $ 47,180