General Motors is the latest OEM to enter the growing North American diesel passenger car segment, unveiling its 2014 Chevrolet Cruze diesel model Feb. 7 at the 2013 Chicago Auto Show.
The Cruze diesel is powered by GM's 2.0-L four-cylinder turbocharged direct-injected diesel producing an estimated 148 hp (110 kW) at 4000 rpm and an estimated 258 lb-ft peak torque (350 N·m) at 2000 rpm. Those power and torque figures are expected to top Volkswagen’s 2013 TDI 2.0-L rated at 140 hp (103 kW) at 4000 rpm and 236 lb-ft (320 N·m) at 1750 rpm.
“We certainly expect to get the [estimated] level of horsepower and torque once the engine is SAE certified,” Michael Siegrist, Assistant Chief Engineer of the Cruze 2.0-L turbo diesel engine, told AEI during a phone interview prior to the Cruze diesel’s Chicago debut.
GM expects the car will achieve average city/highway combined fuel economy greater than 40 mpg.
SCR aftertreatment fitted
Based on GM's Family B diesel architecture used in the European-market Cruze, the engine uses an iron cylinder block with twin balance shafts, an aluminum cylinder head, and aluminum pistons. The DOHC valvetrain is belt driven, and the engine uses an electronically controlled variable-geometry turbocharger.
The common-rail injection system operates at pressures up to 1800 bar (26,100 psi). Peak in-cylinder pressure is 180 bar (2610 psi). Compression ratio is 16.5:1.
According to Siegrist, emission regulations, environmental elements (namely cold starts) and higher altitude driving necessitated certain technical changes for the engine’s North American application. For example, it gains an aluminum intake manifold vs. the European model’s thermoplastic intake manifold. The U.S./Canada application employs ceramic glow plugs instead of metal glow plugs, and engine calibration changes also were made.
The Cruze diesel's exhaust aftertreatment system is similar to the arrangement GM uses on its Chevrolet and GMC HD trucks, which are powered by a 6.6-L Duramax V8. The Cruze will be equipped with a diesel particulate filter (DPF) and selective catalytic reduction (SCR) aftertreatment using diesel exhaust fluid (DEF) injection.
Cruze packages the approximate 4.5-gal (17-L) DEF tank in the car’s trunk. The tank holds enough fluid to provide at least 10,000 mi (16,000 km) of driving between refills, according to GM engineers. Cruze also uses exhaust gas recirculation with a high-capacity cooler and bypass to meet U.S. and Canada emissions requirements.
Germans, Mazda bring new diesel blitz
While the Cruze is Chevrolet’s first U.S.-market passenger car since the Isuzu-powered 1986 Chevette to offer a diesel option, German automakers have had a lengthy run of diesel domination in the U.S.
Volkswagen offers two diesel engines in the U.S. market. The aforementioned 2.0-L is offered in Golf, Jetta, Jetta SportWagen, Beetle, Beetle Convertible, and Passat, while the larger Touareg uses a 3.0-L, 240-hp six-cylinder diesel engine. VW has two different exhaust after-treatment approaches in the U.S. The 2.0-L vehicles except Passat are equipped with a diesel particulate filter and a NOx storage catalytic converter, while Passat and Touareg use a particulate filter and urea-based SCR.
According to VW of America spokesperson Corey Proffitt, “the exhaust aftertreatment solution used on any given model is based on a host of factors that include the engine, vehicle weight, and regulatory NOx/PM requirements.”
BMW’s first four-cylinder diesel offering in North America arrives late this summer. U.S. models will be equipped with particulate filters (same as all BMW diesels) plus SCR, to comply with 50-state emission standards, said the company's powertrain spokesperson Dave Buchko.
The 2014 BMW 3 Series Sedan and Sports Wagon models will offer the four-cylinder diesel. In its European applications, the engine produces approximately 180 hp and 280 lb·ft. It joins the automaker’s current North America diesel offering, a 3.0-L sequential-twin-turbo inline 6 which powers the X5 xDrive35d sports activity vehicle.
A different 3.0-L turbocharged inline six, based on an engine currently offered in Europe, is coming to the U.S. as an option for the 5 Series. “It will not be quite as powerful as the current engine, which produces 265 hp and 425 lb·ft of torque,” noted Buchko.
Audi is adding 3.0-L V6 TDI versions of the A6, A7, A8, and Q5 in the U.S. in 2013. These MY14 vehicles will join the A3, powered by a version of VW's 2.0-L TDI engine, as well as the Q7, powered by the 3.0-L V6 TDI. The A3 Sportback TDI uses a particulate filter, while the 3.0-L TDI V6 engines use SCR technology.
The 2013 Mercedes-Benz lineup in the U.S. includes four-cylinder and V6 turbocharged diesel engines with the company's BlueTEC aftertreatment system including a NOx storage converter, an SCR catalytic converter with AdBlue urea injection, and a particulate filter.
Later this year, Mazda will join GM as the second non-German OEM to offer a diesel passenger car in the U.S., when it launches its Skyactiv-D diesel engine on the 2014 Mazda6. (See www.sae.org/mags/aei/11750.)
The 2014 Jeep Grand Cherokee SUV represents another clean diesel option. The SUV will offer a 3.0-L EcoDiesel V6 that mates to an eight-speed automatic transmission.