Frankfurt 2007: Smart ForTwo micro hybrid launches!

At the Frankfurt Motor Show, Smart has officially launched the micro hybrid version of the ForTwo. Like the mild hybrid system developed by General Motors, this belt-alternator-starter system is primarily an automatic start-stop system for when the car is not moving. Unlike the GM system, the Smart doesn't provide any power boost in motion or do regenerative braking.

The start-stop system will initially only be available with the 71hp gasoline engine and the automated manual transmission. When the vehicle comes to a stop the engine switches off and the clutch disengages. When the driver releases the brake, the engine automatically starts back up. The micro hybrid system is claimed to provide a fuel efficiency improvement eight percent from 50 to almost 55 mpg. Carbon dioxide emissions drop from 112 to 103g/km. The Smart ForTwo micro-hybrid goes on sale in October in Europe and the press release is after the jump.

[Source: Smart]
At the International Motor Show in smart will be presenting three new additions to the successful smart fortwo model range. The smart fortwo micro hybrid drive (mhd) will be presented to the public for the first time. Thanks to micro hybrid drive technology, this version consumes approximately 8 percent less fuel in the combined driving cycle and even up to 20 percent less fuel in urban traffic, which also results in greatly reduced CO2 emissions. The drive unit featured in the new smart fortwo cdi is a masterpiece of engine development. The world's smallest diesel engine uses state-of-the-art common-rail direct injection to achieve exemplary consumption figures. With consumption of 3.3 litres (NEDC) per 100 kilometres and CO2 emissions of just 88 grams per kilometres, it has the lowest CO2 emissions worldwide - earning it the title of "CO2 champion". The smart fortwo BRABUS and the smart fortwo BRABUS Xclusive are further new models. These two models represent the top of the smart fortwo model range and will be launched on 06 October.

From a particularly economical variant of the smart fortwo will roll off the production line: the smart fortwo micro hybrid drive with 52 kW/ 71 bhp. This model features a start/stop function that uses the engines idling phases - a first in a smart! The new model will be available from around the end of October 2007 as a coupé and a cabrio in all three lines - pure, pulse and passion. Moreover, there will be an extremely attractive limited special series to mark the market launch. The smart fortwo micro hybrid drive will initially be available as a left-hand-drive ECE version .

Edition smart fortwo micro hybrid drive

The smart fortwo micro hybrid drive will be presented to the public for the first time in the form of the exclusive limited edition smart fortwo micro hybrid drive. In addition to micro hybrid drive technology, this vehicle also has much more to offer: the coupé has a particularly elegant appearance thanks to the combination of crystal white bodypanels and a tridion safety cell in classy silver.

The 9-spoke alloy wheels add the icing on the cake to the exterior. Passengers take a seat on safety seats with integral seat belts in a tasteful grey. In addition to the safety equipment that comes as standard in all smart vehicles, a whole host of interesting optional equipment is available for the edition smart fortwo micro hybrid drive. The special edition costs € 10,490 (incl. VAT).

smart fortwo micro hybrid drive: Why use petrol when you are not driving?

No exhaust emissions, no noise, no petrol consumption - when the engine would normally be combusting fuel unnecessarily when stationary, the new smart fortwo micro hybrid drive switches it right off whenever the driver brakes and the vehicle's speed falls below 8 km/h. As soon as the driver releases the brake pedal, the engine starts automatically and the journey can continue immediately without a noticeable delay. The driver doesn't need to do anything out of the ordinary; as is typical of smart, there is no need for any clutchwork, changing down or disengaging of gears. Together with the automated manual transmission that comes as standard, the new start/stop technology guarantees comfortable and straightforward driving with reduced fuel consumption. The new technology pays off, because studies have shown that in everyday traffic, vehicles come to a stop every 1.3 kilometres on average.

In conjunction with slightly modified gear ratios, the start/stop system in the new smart fortwo micro hybrid drive leads to a fuel saving of approximately 8 percent in the New European Driving Cycle (NEDC, combined figure).

The standard consumption is reduced by approximately 0.4 litres - from 4.7 litres to around 4.3 litres per 100 kilometres. There is also a corresponding reduction in CO2 emissions from 112 grams to approx. 103 grams per kilometre. And of course, depending on the traffic situation, much higher fuel savings are possible - for example in heavy slow traffic.

Powerful belt-driven starter generator

At the heart of the start/stop system is a special belt-driven starter generator. This replaces and does the work of both the conventional starter and the alternator. When the engine is running, it generates electric current for the vehicle's electrical system, and when the engine needs to be started this is done smoothly in a fraction of a second. The generator of the system developed by smart delivers torque of 42 Newton metres or current of maximum 120 ampere at 14 volts - enough to guarantee a reliable engine start, even at a temperature of minus 25 degrees Celsius.

High demands are made on the belt drive because it has to drive the generator whilst the engine is running, and also to transmit drive torque to the engine in the reverse pulling direction in its function as a starter. This requires a sophisticated system that is able to optimally regulate the belt tension depending on the load. The starter generator is pivoted to ensure this. A coaxial spring-and-shock absorber unit is hinged to it that is supported by the engine block.

To ensure a low-slip and durable connection between the crank assembly and the starter generator, both components were given wider belt pulleys, as was the water pump that is also driven . A six-rib poly-V-belt from Gates transmits the power .

Control unit with integrated power electronics

A control unit that is installed behind the battery recess controls the function of the start/stop system. This communicates with the vehicle's other control units via CAN databus. Integrated power electronics regulate the power of both the starter and the generator. A three-phase cable transmits the generator power of up to 120 ampere. An AGM battery stores the energy for the on-board electrics. The electrolyte is bound in an absorbent glass matt. Its physical properties make it more resistant to varying loaded and unloaded conditions (more cycle resistant) than conventional lead-acid batteries with sulphuric acid electrolyte.
The power electronics of the belt-driven starter generator ensure that the combustion engine is switched off in idle phases. In view of fuel economy and comfort, the electronics switch off the engine at a speed of below 8 km/h if the driver steps on the brake pedal, signalling that he or she wants to stop. The engine starts again as soon as the driver releases the brake pedal. This guarantees an immediate response. The start/stop function can be deactivated if required with a switch on the centre console - until the next starting procedure (ignition off/ignition on).

smart fortwo cdi: The CO2 champion - a masterpiece of engine development

With the development of the world's smallest direct-injection diesel engine, smart has produced a masterpiece of engine development that earns the new smart fortwo cdi the distinction of the world's most economical production car with combustion drive. The 33 kW/45 bhp two-door car consumes just 3.3 litres of fuel (NEDC) per 100 kilometres which means that it can travel approximately 1000 kilometres without refuelling. Emitting just 88 grams of CO2 per kilometre, the smart fortwo diesel is the world champion in low CO2 emissions.

High-tech fuel injection

State-of-the-art common-rail direct injection provides for a combustion process that is even more efficient than that of the well-proven cdi engine from the predecessor model . High injection pressure of up to 1600 bar (previously 1350 bar) is built up, even at low revs, and the fuel is injected into the combustion chambers with new seven-hole injectors. The power and torque have each improved by 10 percent. At the same time, fuel consumption is reduced by 13 percent. Depending on the driving situation and engine load, up to 60 percent of the previously cooled exhaust gases are returned to the combustion chambers.

Like the CDI engines of its sister brand Mercedes-Benz, fuel injection in the smart fortwo cdi is carried out in two phases: a few milliseconds before the main injection a small quantity of diesel is injected into the combustion chambers where it ignites and preheats the cylinders. This results in a noticeably quieter combustion noise level than an engine without this pilot injection. The electronic "brain" of the cdi engine - a high-performance micro-computer that controls the whole engine system - calculates how much fuel is needed and the interval at which pilot injection and main injection take place.

The quick response of the cdi engine is first and foremost thanks to the compact yet extremely effective turbocharger that is housed in the exhaust manifold. Its compressor wheel has a diameter of just 33 millimetres, yet it rotates at up to 280,000 rpm and builds up maximum charge pressure of approximately 1200 millibars. This gives the three-cylinder engine more air to "breathe" and enables it to develop impressive torque, even at low revs: 85 metres are available even from 1500 rpm - more than three quarters of the maximum torque.

This torque curve plays an important part in the fun behind the wheel that drivers experience with every kilometre driven in a smart fortwo cdi. The new smart fortwo cdi accelerates from zero to 100 km/h in 19.8 seconds and reaches a top speed of 135 km/h. It therefore offers a combination of agility, economy and environmental compatibility that is unique in this class.

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