GM introduces new Cadillac 2013 ATS RWD luxury sport sedan; 2 four-cylinder, one V6 gasoline engine options, with diesel in the works
|2013 Cadillac ATS. Click to enlarge.|
On the eve of the Detroit Auto Show, Cadillac introduced the 2013 ATS, a new rear-drive compact luxury sports sedan developed on an all-new, lightweight vehicle architecture. (Earlier post.) GM says the ATS will be able to deliver peak highway fuel economy of more than 30 mpg.
GM is offering a choice of three power-dense engines, including two new four-cylinder units—a standard 2.5L four-cylinder and a 270 hp (201 kW) 2.0L turbocharged four-cylinder—and the new 318 hp (237 kW) 3.6L V-6 currently offered in the 2012 Cadillac CTS. A diesel engine will enter the line-up in the future, GM said. All of the gasoline engines feature direct injection and dual overhead camshafts with continuously variable valve timing, which help optimize power and efficiency, as well as reduce emissions. All of the engines are matched with six-speed transmissions, including the Hydra-Matic 6L45 automatic with tap-shift control, and a six-speed manual available with the turbo engine.
Increased efficiency in the new four-cylinders was achieved partly through lower engine friction, which was reduced by up to 16% using new technologies such as a variable-displacement oil pump and, with the 2.5L, an actively controlled thermostat. Cadillac proprietary computational fluid dynamics (CFD) analysis techniques were used to develop an all-new combustion system with a higher compression ratio, which also helps boost efficiency.
The 2.5L is rated at an estimated 202 horsepower (151 kW) and 191 lb-ft (258 N·m) of torque , while the 2.0T is estimated at 270 hp (201 kW) and 260 lb-ft (353 N·m) of torque. The 3.6L V-6 is rated at an estimated 315 hp (235 kW) and 267 lb-ft of torque (362 N·m).
Features of the four-cylinder engines’ new combustion system deliver improved knock resistance and higher-flowing intake and exhaust ports in the cylinder head, helping increase efficiency, power and torque. The new engines also have increased-authority cam phasing to minimize compromiss between efficiency, performance, emissions and drivability. Some of the elements that contribute to the refinement of both four-cylinder engines include:
Balance shafts located in a module with an integrated oil pump in the oil pan, to reduce noise and vibration;
A strong, stiff forged-steel crankshaft that enables quieter and smoother engine operation at high rpm;
Inverted-tooth chains for the camshaft and balance shaft drives for quieter operation;
A unique two-piece oil pan design, with an aluminum upper section to provide structural support and a stamped steel lower section to dampen overall noise;
A patent-pending cast aluminum bedplate with cast iron bearing cap inserts to help increase dynamic stiffness and reduce noise and vibration; and
Key sound attenuation features, such as a structural front engine cover, structural cam cover, and light weight composite acoustic intake manifold cover.
The 2.5L is tuned to deliver more of its torque at lower rpm, giving the ATS a stronger feel at launch and during on-demand maneuvers, such as passing or accelerating on a freeway entrance ramp.
New 2.0L turbocharged. An all-new 2.0L turbo engine debuts in the ATS. Along with its 270 hp (201 kW), the 2.0T’s torque curve is broad, delivering 90% of its peak torque from 1,500 rpm to 5,800 rpm.
The turbocharger generates up to 20 pounds of boost and its twin-scroll design helps optimize the usable power from the engine, virtually eliminating turbo lag and helping deliver a broad power band. It also gives the engine the rapid throttle responsiveness associated with a higher-displacement, naturally aspirated, high-performance engine. Electronically controlled supporting components, including the wastegate and bypass, help optimize performance and efficiency.
The engine features durability and technological features familiar in premium engines, including low-friction hydraulic roller-finger valve operation and an electronic throttle. A hydraulic tensioner keeps the timing chain adjusted for life, and extended-life spark plugs deliver 100,000 miles (160,000 km) of service. Additional engine features include:
- Precision sand-cast engine block with cast-in-place iron liners;
- Forged steel crankshaft;
- Pistons with jet-spray cooling;
- Modular balance shaft system in the oil pan;
- Rotocast aluminum cylinder head with sodium-filled exhaust valves;
- Dual Overhead Camshaft (DOHC) with continuously variable valve timing;
- Direct injection with cam-driven high-pressure fuel pump;
- Two-stage variable-displacement oil pump; and
- Air-to-air intercooling system.
A Hydra-Matic 6L45 six-speed automatic with tap-shift control is offered with the 2.0T, along with a new Tremec TR3160 six-speed manual. It is similar in design to the high-performance Tremec TR6060 transmission found in the CTS-V series, delivering the same balance of shift performance and short, precise gear changes. The transmission features carbon synchronizers for reduced shift effort, hard-finished gears for greater refinement and gear ratios tailored to the turbocharged engine’s broad torque band.
The Tremec transmission also contributes to the ATS’s low curb weight, with hollow gears, strategically formed castings and optimized gear profile cross sections. Even the oil volume is optimized for minimal weight.
Lightweight 3.6L. The ATS’s available 3.6L V-6 is the same LFX-code engine introduced in the 2012 CTS. Although it is the largest engine in the ATS powertrain lineup, it still contributes to a low overall vehicle weight, with low-mass features that help maintain the car’s favorable power-to-weight ratio and a front-to-rear weight balance of nearly 50/50.
The lightweight features include:
- Cylinder block and cylinder heads cast in aluminum.
- A composite intake manifold that saves approximately 5.5 pounds (2.5 kg) over the weight of a comparable aluminum intake. It also has a comparatively small radiated surface area to help maintain excellent noise and vibration characteristics.
- An integrated cylinder head/exhaust manifold design saves approximately 13 pounds (6 kg) per engine when compared with a comparable engine with separate head/manifold assemblies.
- Connecting rods made of powdered metal with a higher ratio of copper, which makes them stronger and reduces weight.
- Pistons made of lightweight cast aluminum, which means less reciprocating mass in the engine for less inertia and greater operating efficiency.
Other engine features enhance performance, efficiency and refinement, including:
- A forged steel crankshaft that increases durability and contributes to greater high-rpm smoothness.
- A friction-reducing polymer coating on the piston skirts, as well as fully floating wrist pins, to reduce friction.
- Pressure-actuated oil squirters that drench the underside of each piston and the surrounding cylinder wall with an extra layer of cooling, friction-reducing oil.
- A stiffer cast aluminum oil pan to improve powertrain rigidity and reduce vehicle vibration. It bolts to the transmission bell housing as well as the engine block, eliminating points of vibration.
- Optimized-flow fuel injectors and integrated exhaust manifolds/cylinder heads to reduce emissions.
- Like the 2.5L, the 3.6L V-6 is matched exclusively with the Hydra-Matic 6L45 six-speed automatic transmission with tap-shift control.
Weight. Engineers focused on making the Cadillac ATS one of the lightest cars in the compact luxury segment. Its curb weight of less than 3,400 pounds (1,542 kg) is a key contributor to its driving experience and helps make the new sport sedan more efficient. An aluminum hood, magnesium engine mount brackets and lightweight, natural-fiber door trim panels contribute to the ATS’s low overall mass.
High-strength steel (HSS) and ultra-high-strength steel (UHSS) are used to reduce mass and optimize crash protection. The ATS features UHSS in areas such as cross-vehicle beams around the “safety cage” of the body structure.
ATS powertrain and suspension systems feature extensive use of aluminum. Many of the links for the front suspension are aluminum, as well as the front suspension cradle on both rear-wheel-drive and all-wheel-drive models.
The aluminum-intensive powertrains not only helped minimize overall weight, they are instrumental in favorable power-to-weight ratios that contribute to the ATS’s feeling of performance.
The 2013 Cadillac ATS goes on sale during the second half of 2012.