GM has unveiled their BMW 3 Series competitor, the 2013 Cadillac ATS. The car is based on a new, lightweight, RWD architecture which enables it to weight less than 3,400 lbs (1,542 Kg) and it will go on sale this summer.
Described as a "blend of technologically driven performance, elegance and design" the 2013 Cadillac ATS measures has been "designed with quick, nimble and fun-to-drive dynamics" and it "expands Cadillac’s portfolio into a crucial global segment".
This all-new compact luxury sports sedan features an almost perfect 50/50 weight balance, uses the company’s first 5-link independent rear suspension, has a multi-link double-pivot MacPherson-strut front suspension with direct-acting stabilizer bar, with the driver being able to adjust the settings of the Magentic Ride Control.  
The engines available for the 2013 Cadillac ATS include two 4-cylinder units (an all-new 2.0-litre turbo rated at 270 horsepower / 201 kW plus a 2.5-litre unit producing 200 HP / 149 kW) as well as a  3.6-litre V-6 expected to deliver 320 horsepower (238 kW).
During the development phase the new ATS was extensively tested on the Nurburgring, and some of the components that contribute to its performance are also the belt driven electric variable-effort steering gear from ZF and the four-channel ABS backed by the Brembo performance brakes.
Transmission options on the 2013 ATS include both manuals and automatics along with rear-wheel and all-wheel-drive configurations, and in terms of efficiency the 2.0T model is expected to return more than 30 mpg on the highway. 

Overview

Model: Cadillac ATS Sedan
Body style / driveline: 4-door luxury sport luxury sedan, RWD/AWD
Construction: Unitized welded steel body with direct-mounted front cradle and rubber-isolated, multi-link independent rear suspension
EPA vehicle class: small car
Manufacturing location: Lansing Grand River Assembly, Lansing, Mich.

Engines

  2.0L Turbo DI VVT 2.5L I-4 DI VVT 3.6L V-6 DI VVT
Displacement (cu in / cc): 122 / 1998 150 / 2457 217 / 3564
Bore & stroke (in / mm): 3.39 x 3.39 / 86 x 86 3.46 x 3.97 / 88 x 101 3.7 x 3.37 / 94 x 85.6
Block material: cast aluminum cast aluminum cast aluminum
Cylinder head material: cast aluminum c ast aluminum cast aluminum
Valvetrain: DOHC, four-valves per cylinder, continuously variable valve timing DOHC, four valves per cylinder, continuously variable valve timing DOHC, four valves per cylinder, continuously variable valve timing
Fuel delivery: direct high-pressure fuel injection direct high-pressure fuel injection direct high-pressure fuel injection
Compression ratio: 9.2:1 11.4:1 11.5:1
Horsepower (hp / kW @ rpm): 270 / 201 @ 5300 (est) 200 / 149 @ 6200 (est) 318 / 237 @ 6800 (est – gas)
Torque (lb-ft / Nm @ rpm): 260 / 353 @ 2400 (est) 188 / 255 @ 4500 (est) 267 / 362 @ 4900 (est – gas)
Recommended fuel: premium recommended but not required regular unleaded regular unleaded or E85
Maximum engine speed (rpm): 6350 7000 7200
Estimated fuel economy: TBD TBD TBD

Transmission

  Tremec M3L TR3160 Hydra-Matic 6L45
Type: fully synchronized six-speed manual with single overdrive six-speed, electronically controlled, automatic overdrive with torque converter clutch
Gear ratios (:1):    
First: 4.12 4.06
Second: 2.62 2.37
Third: 1.81 1.55
Fourth: 1.30 1.16
Fifth: 1.00 0.85
Sixth: 0.80 0.67
Reverse: 3.75 3.20
Final drive ratio: 3.27 3.27 (2.5L, 3.6L)
3.45 (2.0T)

Chassis/Suspension

Configuration: rear-wheel drive
Differential: open (FE2 suspension); mechanical limited-slip (FE3 suspension)
Front: MacPherson-type with dual lower ball joints and direct-acting stabilizer bar; Magnetic Ride Control (FE3)
Rear: independent five-link with monotube shock absorbers; Magnetic Ride Control (FE3)
Steering type: ZF rack-mounted electric, power-assisted and variable assist
Steering ratio: FE2: 16.8:1
FE3: 15.3:1
Steering turns, lock-to-lock: FE2: 3.16
FE3: 2.86
Turn circle (ft / m): FE2 RWD: 36.38 / 11.09
FE3 RWD: 35.99 / 10.97
FE2 AWD: 38.05 / 11.60
Chassis control: four-channel StabiliTrak w/ brake assist and traction control

Brakes

Type: four-wheel disc with sliding calipers on
base; four-channel ABS/TCS w/ DRP; Brembo brakes with fixed calipers on
Luxury, Performance and Premium collections
Rotor type and thickness (in / mm): Standard front: 11.8 x 1.02 (300 x 26) vented, with Ferritic Nitro Carbunized process for corrosion resistance
Standard rear: 12.4 x 0.90 (315 x 23) vented, with Ferritic Nitro Carbunized process for corrosion resistance
Uplevel front: 12.6 x 1.18 (321 x 30) vented, with Ferritic Nitro Carbunized process for corrosion resistance
Uplevel rear: 12.4 x 0.90 (315 x 23) vented, with Ferritic Nitro Carbunized process for corrosion resistance

Wheels/Tires

Wheel size and type: 17×8-inch aluminum (painted)
17×8-inch aluminum (polished)
18×8-inch aluminum (machined-face)
18×8-inch aluminum (polished)
Tire size: P225/45R17 90H all-season
P225/45R17 90V run-flat all-season
225/40R18 92V run-flat all-season
225/40R18 88W / 255/35R18 90W run-flat summer-only
225/35ZR19 88Y / 255/30ZR19 91Y run-flat all-season (LPO)

Dimensions

Exterior

Wheelbase (in / mm): 109.3 / 2775
Length (in / mm): 182.8 / 4643
Height (in / mm): 55.9 / 1421
Width (in / mm): 71.1 / 1805
Track (in / mm): front: 59.5 / 1512
rear: 60.9 / 1548
Curb weight (lb / kg): less than 3,400 / 1,542 (approx.)
Weight distribution (% front / rear): 51 / 49

Interior

Legroom (in / mm): front: 42.5 / 1079
rear: 33.5 / 851
Headroom (in / mm): front: 38.6 / 980
rear: 36.8 / 935
Shoulder room (in / mm): front: 55.2 / 1345
rear: 53.9 / 1370
Hip room (in / mm): front: 53.0 / 1345
rear: 52.3 / 1328

Capacities

Seating capacity (front / rear): 2 / 3
EPA passenger volume (cu ft / L): 90.9 / 2573
EPA trunk volume (cu ft / L): 10.2 / 290
Trailer towing maximum (lb / kg): 1000 / 454 (3.6L)
Fuel tank (gal / L): 16 / 60.5
Engine oil (qt / L): TBD
Cooling system (qt / L): 8.1 / 7.7 (2.0T)
7.1 / 6.7 (2.5L)
11 / 10.4 (3.6L)
Source: GM