SmILE

The 1996 public for the Twingo SmILE is a prototype car based on the Renault Twingo, the fuel consumption has been reduced by half. Smile stands for small, smart, light and efficient.

The aim of reconstruction

Greenpeace wanted to prove that it is possible to produce low-energy vehicles without large costs and material costs. The primary objective was to develop a production car rebuild so that it at the same or slightly higher price only half consumed fuel. The vehicle should meet the following criteria:

• Entered series small car with 4 seats and about 55 hp as a basis
• Meet the everyday demands of the average car driver, as a complete replacement for a conventional vehicle
• Using a gasoline engine since that time about 80 % of the vehicles were equipped with such an engine worldwide and a diesel engine emits carcinogenic soot particles
• Great series -ready concept.

The Renault Twingo met these requirements. He also offered with the 1993 installed as standard OHV cast iron engine, an outdated engine from the Renault R12, the opportunity to demonstrate the potential for weight saving and consumption reduction particularly clear.

Implementation and financing

The Swiss Federal Office of Energy and Greenpeace entrusted the Swiss company Wenko with the development of an appropriate vehicle. Greenpeace gave its subsidy as a credit in the amount of DM 2.5 million ( € 1.3 million), which was only in the event of an economic success refundable.

Wenko self-developed drive technology. Esoro drew it responsible for the reduction of vehicle weight at the cell, reducing the air resistance and the reduction of the rolling resistance.

Air resistance

Through work in the wind tunnel at SF Emmen ( today RUAG ) could drag coefficient from 0.371 to 0.246 ( 0.63 to 0.48 m ) are reduced. This was done by cultivation of plastic parts that were made ​​by BRM style.

Rolling friction

Weight reduction

The weight was reduced by 150 kg to the vehicle, which are due in roughly equal to the lighter engine and the use of aluminum parts on the body and the chassis. The seats have been simplified. The tank capacity was reduced to 20 l.

Engine technology

Wenko developed a two-cylinder four -valve boxer engine of 358 cc DOHC design. The compression ratio was 10:1. The engine had a compression wave charger with a charge of 1.6. This provided at a mean pressure of 26 bar already at 3000 rpm for a torque of 75 Nm. The power was 40 kW ( 55 hp ) at 5500 rpm. The installation weight with all parts was 35 kg.

This engine was at part load, ie the general driving range, work without charging a very high intake manifold pressure. Only for acceleration or for a high speed charging, and also the full engine power was required. The best specific fuel consumption was achieved at 4500 rpm and about 27 hp. He was 259 g / kWh, a rather average value (see Common Rail Diesel: < 198 g / kWh). Technically, it was important that the part -load range very widely failed for a gasoline engine, so that the typical load case could be driven with a similarly low specific fuel consumption, as with a diesel engine.

Prototype

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

The average fuel consumption according to NEDC was reduced from 6.7 l to 3.26 l to 3.75 l. For economical driving style, it was possible to reduce the consumption to less than 3 l/100 km.

The vehicle has been used in several experimental and demonstration rides on about 50,000 km. A tester of the magazine Auto Bild certified that the vehicle performance that rival any production model in nothing.

With the Twingo Smile was trying to show that by making use of all technical possibilities of his time, a reduction in fuel consumption NEDC by 50 % could be possible. Overall, the concept study met with the vehicle manufacturers and consumers of little interest.

Resonance

Neither Renault Twingo, the manufacturer of other car manufacturers showed after the study is interested in the series production, despite the pronounced compared to the normal development of a new type of vehicle low development costs. Greenpeace environmental organization has been also made no production vehicles.

Greenpeace itself stated that with this change essentially a reduction in fuel consumption for each vehicle series of approximately 50 % (as of 1996) is possible.

Greenpeace continued to lead as the reason for the lack of interest on the part of the manufacturer that the commercial vehicles sold well. A change of models according to the model of the Twingo Smile would involve a major in the design and manufacturing result, which would initially incur costs. In the medium term, these investments could pay off, however, as international demand for low emission vehicles likely would rise.