14 June 2007

DaimlerChrysler has introduced a new version of the smart fortwo cdi, a diesel city car that offers fuel consumption of 3.3 l/100 km (71 mpg US) and CO2 emissions of 88 g/km.

The new smart fortwo cdi is powered by an improved three cylinder, 799 cc engine that develops 33 kW (45 bhp) of power and 110 Nm of torque between 2000 and 2500 rpm. Compared to the previous model, the power and torque have increased by 10%, whilst the fuel consumption has decreased by 13%. The smart fortwo cdi accelerates from 0-100 km/h in 19.8 s and reaches a top speed of 135 km/h.

The new cdi direct injection engine features a common-rail fuel system with up to 1,600 bar (previously: 1,350 bar) injection pressure and six-hole injectors. A two-phase fuel injection has been adopted from the CDI Mercedes-Benz engines, where a pilot injection occurs a few milliseconds before the main injection to control combustion noise.

For a quick response, the cdi engine is fitted with a compact turbocharger that is housed in the exhaust manifold. The compressor wheel has a diameter of just 31 mm, and rotates at up to 290,000 rpm, building up a maximum charge pressure of approximately 1,150 mbar.

For NOx control, the engine uses cooled exhaust gas recirculation (EGR) with an electropneumatic actuator and up to 60% EGR rates. The exhaust aftertreatment system includes a diesel oxidation catalyst and a flow-through (“open”) filter which are housed together with the exhaust silencer in a stainless steel case. The smart fortwo cdi is Euro 4 compliant.

DaimlerChrysler initially advertised the vehicle as having “extremely low emission values”. After a complaint by Deutsche Umwelthilfe, a German environmental organization, a court in Stuttgart ordered DaimlerChrysler to remove this phrase from all advertisements, as the smart fortwo cdi produces higher PM emissions than many larger cars equipped with wall-flow diesel particulate filters.

DaimlerChrysler said it is considering the use of a wall-flow diesel particulate filter in 2008. For now, the vehicle is advertised as the world’s most economical production car with the lowest CO2 emissions.

Source: DaimlerChrysler, Spiegel