HELEN, Ga. -- Chattahoochee River Road is a narrow blacktop ribbon -- tracing every twist and bend of a whitewater sluice in the Blue Ridge ripples of northern Georgia -- where we're gripping a leather-clad steering wheel and drawing on twin-turbocharged muscle to push the pace in a souped-up 2015 XTS VSport, Cadillac's big mid-size luxury touring sedan.
This red-hot touring car, riding on a rigid front-wheel-drive platform with independent suspension elements at all corners plus standard Magnetic Ride Control variable shock damping to control wheel and body motion via magnetized fluid in shocks, packs a goosy twin-turbo V6 engine and distributes it to all four of the 20-inch aluminum wheels wrapped in 245/40R20 all-season blackwalls.
XTS in 4-door sedan format has a 111.7-inch wheelbase with a wheel track width of 62.3 inches in front and 62.5 inches in back, an overall length of 202 inches, width of 72.9 inches and a rooftop height of 59.4 inches. Its passenger compartment -- with 2 + 3 seating -- comprises a generous 104.2 cubic feet with 18 cubic feet for trunk volume, which places the big car at the top of the EPA's mid-size class.
The 2015 editions of XTS rank as Cadillac's most technologically advanced production cars, as each stocks a host of high-tech electronic controls plus OnStar with 4G LTE and standard Wi-Fi as a mobile hotspot.
Cadillac constructs the 2015 XTS with two powertrain choices, the XTS 3.6-liter V6 and the VSport twin-turbo V6. XTS offers four trim levels (Standard, Luxury, Premium, Platinum) and XTS VSport has two trims (Premium, Platinum).
The XTS carries an aluminum 3.6-liter V6 engine rigged with dual overhead cams, direct injection technology and variable valve timing. With direct injection, the fuel goes directly into the engine's combustion chamber and fosters a thorough burn of the mix of air and fuel.
The V6 produces 305 hp at 6800 rpm, with torque peaking to 264 lb-ft at 5200 rpm.
Stock transaxle on XTS is a smooth-to-shift electronically controlled 6-speed automatic, GM's Hydra-Matic 6T70 with tap-shift control via paddles on the steering wheel.
Traction choices include standard front-wheel-drive or on-demand all-wheel-drive with Haldex technology and an electronic limited-slip differential that splits torque between the rear wheels.
XTS VSport totes an aluminum 3.6-liter twin-turbocharged V6 that rips to 410 hp at 6000 rpm with torque of 369 lb-ft between 1900-5600 rpm. Its transmission is GM's Hydra-Matic 6T75, also with tap-shift control.
All of the go-power for XTS issues is countered by a 4-wheel disc brake system by the Brembo brand from Italy with vented rotors and electronic links to an anti-lock brake system (ABS) and traction control system (TCS) plus vehicle skid controls.
Standard wheels are 19-inch painted aluminum with chrome inserts and 245/45R19 all-season blackwall tires. The Platinum grade gets 20-inch polished aluminum wheels with the 245/40R20 all-season tires.
Sheetmetal styling on XTS looks crisp. The aggressive face features a prominent horizontal louver panel in modern interpretation of the Cadillac classic egg-crate grille, and piercing optics with stacked round high-intensity discharge xenon lamps that swivel in concert with the vehicle's front wheels via the Adaptive Forward Lighting device on the top two XTS trim tiers.
Inside a spacious cabin with seats for five, the exterior theme of chiseled forms and angular features is expressed in a monochromatic treatment with hand-cut, hand-sewn and hand-wrapped surfaces and leather upholstery as standard equipment.
For XTS Standard and Luxury grades, the instrument panel employs conventional analog gauges. On XTS Premium and Platinum, the gauge cluster amounts to a full-color 12.3-inch thin-film transistor display that's re-configurable.
Cadillac's electronics interface -- CUE -- brings a touch-sensitive 8-inch display in the center stack and steering wheel tabs to control climate, audio, phone and optional navigation functions with finger touching, swiping and pinching movements as used with tablets and smartphones.
Cadillac posts 2015 MSRP points at $44,660 for XTS FWD Standard and $51,000 for XTS AWD Luxury. XTS VSport AWD Premium lists for $62,735 and XTS VSport AWD Platinum hits $69,785.