Smart ForTwo Hybrid

Daimler Chrysler’s Smart division has developed a series of concept test cars that incorporate a range of advanced and alternative-fuel technologies: gasoline and diesel hybrids, cng-fueled, and electric.

These follow on the premiere of the Crosstown Hybrid showcar concept presented at the Frankfurt auto show in September. There is no commitment from Smart to commercialize any of these.

The Smart Crosstown Gasoline Hybrid

The Crosstown Smart car prototype combines an electric motor (with an output of up to 23 kW) with the 45 kW (61 hp) gasoline engine from the Smart Fortwo.

The result is a 15% reduction in fuel consumption to 4.3 liters of gasoline per 100 kilometers (55 mpg US). The Smart Crosstown furthermore offers approximately 10% better acceleration (the production car requires 15.5 seconds to accelerate from 0 to 100 km/h).

The mild hybrid system offers start-stop capability as well as assistance during acceleration and during gear changes.

Instead of using a conventional automatic transmission and torque converter, the Smart Crosstown works with a manual transmission mechanism including friction-disc clutch. The advantages of this compared with a fully automatic transmission lie in the much higher efficiency, lower weight, more compact dimensions and lower production costs.

However, unlike an automatic transmission, this principle causes traction interruptions between opening and closing the clutch for gear shifting. In the Smart Crosstown these are bridged by the electric motor. For a few tenths of a second it supplies the propulsion power needed, enabling harmonious, steady acceleration over the whole gear spectrum.

Smart Fortwo Micro Hybrid

A Micro-Hybrid version of the Smart Fortwo uses a belt-driven starter generator in combination with the 45 kW (61 hp) gasoline engine to reduce fuel consumption by 5%.

The Micro-Hybrid version offers no regenerative braking, nor any tractive assist. It does provide start-stop functionality.

With the Micro-Hybrid the standard fuel consumption level of 4.7 litres per 100 kilometers (50 mpg US) is reduced by 0.25 litres to less than 4.5 liters (52 mpg US). In urban traffic, the Smart Fortwo Micro Hybrid uses a 13% less gasoline. This was a prototype and it’s a different car than the Smart ForTwo 451 Mhd that was released in 2008.

Smart Fortwo CDI Hybrid

The diesel hybrid version of the Smart car consumes just 2.9 liters of fuel/100 km (81 mpg US).

The diesel hybrid combines a 20 kW electric motor with the 30 kW (40 hp) diesel engine. The design is much the same as the Crosstown Hybrid, with the electric motor providing start-stop functionality, drive assistance, shift delay bridging and regenerative braking.

Because the car’s shift delays are bridged by the electric motor, it only needs 17.8 seconds to accelerate from zero to 100 km/h. That’s ten percent—two seconds—better than with a conventional diesel drive.

Source: Green Car Congress