Twingo smile

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Twingo SmILE
Presentation year: 1996
Vehicle fair: IAA 1997
Class : Microcar
Body shape : Station wagon
Engine: Otto engine :
0.36 liters (40 kW)
Length: 3480 mm
Width: 1760 mm
Height: 1423 mm
Wheelbase: 2345 mm
Empty weight: 650 kg
Production model: none

The Twingo SmILE is commissioned by Greenpeace developed three-liter car based on the Renault Twingo I . Its prototype was presented to the public in 1996 and reduced the fuel consumption of the basic vehicle by half. The name “SmILE” stands as an acronym for the concept: “ Sm all. I ntelligent. L ight. E fficient. "

Greenpeace used the vehicle, including the motto "The first step - half fuel" for his in 1993 launched climate - campaign to reduce energy consumption in transport.

Goal of the concept

Greenpeace wanted to prove that the high cost and material expenditure alleged by the automotive industry and other lobbyists for the production of low-energy vehicles was an advance. The primary goal was therefore to convert a series vehicle that would cut NEDC fuel consumption in half at the same or at least slightly higher price . The vehicle should meet the following criteria:

  • Small car from series production with 4 seats and around 55 hp as the basis;
  • Otto engine instead of diesel engine , as there are no soot particles and completely dominant in global use;
  • A concept suitable for large-scale production that meets the everyday demands of average motorists just as well as the basic model.

The Renault Twingo , introduced in 1993, met these requirements. In addition, the engine that was installed as standard had great potential for weight savings and lower fuel consumption, as its concept with a cast iron engine block and side camshaft came from the Renault 8 from the early 1960s.

execution

Greenpeace and the Federal Energy Agency entrusted the Swiss Wenko AG with the development of a corresponding vehicle. Greenpeace granted its grant in the form of a loan of 2.5 million DM (1.3 million €), which could only be repaid in the event of economic success. Wenko developed the drive technology himself. Esoro worked on the body, lowered the vehicle weight and reduced air and rolling resistance .

Air resistance

By working in the wind tunnel at SF Emmen (today RUAG ), the drag coefficient was reduced from 0.371 to 0.246 ( from 0.63 to 0.48 m²). This was done by adding plastic parts made by BRM Design .

Rolling friction

By using particularly low-resistance and narrow tires, the rolling friction was reduced from 0.012 to 0.008.

Weight saving

The weight of the vehicle has been reduced by 150 kg, half of which can be attributed to the lighter engine and the use of aluminum parts on the body and chassis . The seats have been simplified. The tank capacity has been reduced to 20 liters.

Engine technology

Wenko developed a two-cylinder boxer engine with a displacement of 358 cm³ , each with an overhead camshaft that operated four valves via roller rocker arms. The compression ratio was 10: 1. A pressure wave supercharger with a maximum boost pressure ratio of 3 provided a torque of 75 Nm at a mean pressure of 26 bar at 3000 rpm, while the maximum output of 40 kW (55 hp) was only achieved at 5500 rpm. The installation weight with all attachments was only 35 kg.

This engine was able to work in the partial load range, i.e. the general driving range, with a very high intake manifold pressure without charging. Charging and full engine power were only required for acceleration or for high speed. The best specific consumption of 259 g / kWh was achieved at 4500 rpm and around 27 hp. It was technically important that the partial load range for a gasoline engine turned out to be very broad, so that in the typical load case it was possible to drive with a similarly favorable specific consumption as with a diesel engine .

Result

The prototype showed good driving performance. The acceleration was on par with the original model. The maximum speed is estimated at 170 km / h due to the better aerodynamics and would be 15 km / h higher than the original type. However, the vehicle was never extended.

The first comparison with a series Twingo over a 150 km test drive resulted in 3.3 versus 6.7 l / 100 km; The average fuel consumption according to the NEDC was determined to be 3.5 l / 100 km. Energy-saving driving style made it possible to consume less than 3 l at a maximum of 90 km / h.

The vehicle was used in several test and demonstration drives over approximately 50,000 km. A tester from Auto Bild magazine attested the vehicle's performance that was in no way inferior to the production model.

Greenpeace concluded from the study that with the concept used, it was relatively easy to achieve a reduction in fuel consumption of 50% for all production vehicles at the time.

resonance

Overall, the concept study met with little interest from vehicle manufacturers and consumers. Neither Renault, as the manufacturer of the Twingo, nor other car manufacturers showed any interest in series production after the study was completed, despite the extremely low development costs compared to the normal development of a new vehicle type.

Greenpeace continued to cite the reason for the lack of interest on the part of manufacturers that the off-the-shelf vehicles were selling well. A conversion of models based on the Twingo Smile model would result in considerable changes in planning and production, which would initially be associated with costs. In the medium term, however, these investments could pay off, since the international demand for low-emission vehicles is likely to increase.

See also

Web links

Individual evidence

  1. ↑ Smile: The first step, half the fuel. greenpeace.de, 2006, accessed on May 25, 2019 .
  2. ↑ a b Smile: The most important points in brief. greenpeace.de, accessed on May 25, 2019 .
  3. ↑ Smiled at first, then copied. greenpeace.de, 2011, accessed on May 25, 2019 .
  4. ↑ Lino Guzzella , Roger Martin: The SAVE engine concept. In: Motortechnische Zeitschrift 59, 1998, accessed on May 25, 2019 .