SmILE
Encyclopedia
SmILE is a showcase car
designed for Greenpeace
in 1996 to demonstrate how fuel efficient a car can be. The name stands for "Small, Intelligent, Light, Efficient'. It is based on the Renault Twingo
, halving its fuel consumption to 3.3 l/100km
(30 km/l or 85 mpg (imperial) / 68mpg (US)).
An important issue in the design was that it should use off-the-shelf technology (parts and knowhow). As a result, in mass production it should not cost significantly more than a 'heavier' equivalent. The engine should even be cheaper because it is made of fewer parts. However, parts that would be more expensive are supercharging (be it pressure wave supercharger
or turbo-supercharger) and the wheels and the wheel suspension, which are made of aluminium.
The major changes made to the Twingo are:
The main consumption change of the engine stems from its more frequent use in the higher load range, which results in higher thermal stress. This is compensated for by an ingenious cooling system. The mean piston
velocities are in the customary range. The use of the latest technologies in materials and surface coatings guarantees stability of piston rings and cylinder bearing surfaces despite the higher pressures due to supercharging.
At least a further 80 kg weight reduction could be achieved through the use of fibre composite material
s, a smaller tank and replacing the glass windows with polycarbonate
. A further redesign could improve the fuel consumption even more, such as an even smaller engine, further weight savings, improving the aerodynamics
(e.g., through a smaller rear interior), automatic inertia
utilisation or engine switch-off systems, regenerative braking, etc.
The changes did not alter the safety standards of the Twingo and the airbag
and lateral collision protection were kept in place.
Aluminium
accounts for 45 kg of the weight of the SmILE (7%), through replacement of both axles, wheel suspension and seat structure. In average cars in Europe this is 65 kg (6%) and rising. One problem with aluminium is the high energy cost of primary production. However, recycled aluminium has a much lower energy cost and identical mechanical properties.
In Germany
, around 10% of all cars are replaced annually by new vehicles, so if all new vehicles had the SmILE standard that would mean an annual reduction of the CO2 emissions
of the car fleet by 5%.
A similar reduction in fuel consumption would be possible for all petrol cars, but not diesels
because they are heavier (and require heavier batteries). The Twingo was chosen because of its favourable ratio between internal space and exterior and because it is a reasonable all-round car for everyone (it is the most imported car in Germany).
Greenpeace says that ultimately, this car is not a definitive solution. Reduction of the number of cars is still necessary, also to reduce other problems, such as traffic jams, the emission of toxic substances in cities, the death toll on roads
(over a million per year) and the destruction (and carving up) of nature to build roads. Alternative fuels would be a better solution, but time is pressing, so an intermediate off-the-shelf solution like the SmILE is needed.
The car was designed by the Swiss
company of Wenko. For this, they received a loan of roughly 1.3 million euro
from Greenpeace, which they will return if the engine concept is taken over by a manufacturer for series production or profits are obtained from issuing licences.
Čar
Čar is a village in the municipality of Bujanovac, Serbia. According to the 2002 census, the town has a population of 296 people.-References:...
designed for Greenpeace
Greenpeace
Greenpeace is a non-governmental environmental organization with offices in over forty countries and with an international coordinating body in Amsterdam, The Netherlands...
in 1996 to demonstrate how fuel efficient a car can be. The name stands for "Small, Intelligent, Light, Efficient'. It is based on the Renault Twingo
Renault Twingo
The Renault Twingo is a city car built by French automaker Renault, first presented at the Paris Motor Show in September 1992 and sold in continental European markets beginning in 1993...
, halving its fuel consumption to 3.3 l/100km
Fuel economy in automobiles
Fuel usage in automobiles refers to the fuel efficiency relationship between distance traveled by an automobile and the amount of fuel consumed....
(30 km/l or 85 mpg (imperial) / 68mpg (US)).
An important issue in the design was that it should use off-the-shelf technology (parts and knowhow). As a result, in mass production it should not cost significantly more than a 'heavier' equivalent. The engine should even be cheaper because it is made of fewer parts. However, parts that would be more expensive are supercharging (be it pressure wave supercharger
Pressure wave supercharger
A pressure wave supercharger is a type of supercharger technology that harnesses the pressure waves produced by an internal combustion engine exhaust gas pulses to compress the intake air. Its automotive use is not widespread; the most widely used example is the Comprex, developed by Brown Boveri...
or turbo-supercharger) and the wheels and the wheel suspension, which are made of aluminium.
The major changes made to the Twingo are:
- 23% lighter (650 kg instead of 845 kg):
- 80 kg less because of a smaller engine and lighter peripherals (battery, radiator and exhaust system)
- 80 kg less in vehicle interior and chassis through lighter seat structures (aluminiumAluminiumAluminium or aluminum is a silvery white member of the boron group of chemical elements. It has the symbol Al, and its atomic number is 13. It is not soluble in water under normal circumstances....
/ plasticPlasticA plastic material is any of a wide range of synthetic or semi-synthetic organic solids used in the manufacture of industrial products. Plastics are typically polymers of high molecular mass, and may contain other substances to improve performance and/or reduce production costs...
) and lighter metals for wheel suspensions, drum brakes, brake calliper and rims. To keep the cost down, no exotic materials (such as titaniumTitaniumTitanium is a chemical element with the symbol Ti and atomic number 22. It has a low density and is a strong, lustrous, corrosion-resistant transition metal with a silver color....
screws or carbon gear boxes) were used. - lighter wheels, which also have a rolling resistance that is 35% lower.
- Less air resistance, with a 30% improvement in the wind tunnel (Cw value (drag coefficientDrag coefficientIn fluid dynamics, the drag coefficient is a dimensionless quantity that is used to quantify the drag or resistance of an object in a fluid environment such as air or water. It is used in the drag equation, where a lower drag coefficient indicates the object will have less aerodynamic or...
) down from 0.37 to 0.25) - A smaller and more efficient engine, a supercharged flat-twin, four-stroke engine with four-valve technology in a boxer arrangement. A maximum torqueTorqueTorque, moment or moment of force , is the tendency of a force to rotate an object about an axis, fulcrum, or pivot. Just as a force is a push or a pull, a torque can be thought of as a twist....
of 75 N·m results from a swept volume of 358 cm3 at 2,900 rpm. The dynamic pressure supercharger makes sure the engine runs most efficiently at normal operating speeds. Most car engines are designed for optimum performance at maximum speed and load, which are in reality rarely used. At 55 bhp, the engine has the same performance as the original Twingo. Other performance parameters, such as maximum speed, elasticity and accelerationAccelerationIn physics, acceleration is the rate of change of velocity with time. In one dimension, acceleration is the rate at which something speeds up or slows down. However, since velocity is a vector, acceleration describes the rate of change of both the magnitude and the direction of velocity. ...
are the same or better.
The main consumption change of the engine stems from its more frequent use in the higher load range, which results in higher thermal stress. This is compensated for by an ingenious cooling system. The mean piston
Piston
A piston is a component of reciprocating engines, reciprocating pumps, gas compressors and pneumatic cylinders, among other similar mechanisms. It is the moving component that is contained by a cylinder and is made gas-tight by piston rings. In an engine, its purpose is to transfer force from...
velocities are in the customary range. The use of the latest technologies in materials and surface coatings guarantees stability of piston rings and cylinder bearing surfaces despite the higher pressures due to supercharging.
At least a further 80 kg weight reduction could be achieved through the use of fibre composite material
Composite material
Composite materials, often shortened to composites or called composition materials, are engineered or naturally occurring materials made from two or more constituent materials with significantly different physical or chemical properties which remain separate and distinct at the macroscopic or...
s, a smaller tank and replacing the glass windows with polycarbonate
Polycarbonate
PolycarbonatePhysical PropertiesDensity 1.20–1.22 g/cm3Abbe number 34.0Refractive index 1.584–1.586FlammabilityV0-V2Limiting oxygen index25–27%Water absorption – Equilibrium0.16–0.35%Water absorption – over 24 hours0.1%...
. A further redesign could improve the fuel consumption even more, such as an even smaller engine, further weight savings, improving the aerodynamics
Aerodynamics
Aerodynamics is a branch of dynamics concerned with studying the motion of air, particularly when it interacts with a moving object. Aerodynamics is a subfield of fluid dynamics and gas dynamics, with much theory shared between them. Aerodynamics is often used synonymously with gas dynamics, with...
(e.g., through a smaller rear interior), automatic inertia
Inertia
Inertia is the resistance of any physical object to a change in its state of motion or rest, or the tendency of an object to resist any change in its motion. It is proportional to an object's mass. The principle of inertia is one of the fundamental principles of classical physics which are used to...
utilisation or engine switch-off systems, regenerative braking, etc.
The changes did not alter the safety standards of the Twingo and the airbag
Airbag
An Airbag is a vehicle safety device. It is an occupant restraint consisting of a flexible envelope designed to inflate rapidly during an automobile collision, to prevent occupants from striking interior objects such as the steering wheel or a window...
and lateral collision protection were kept in place.
Aluminium
Aluminium
Aluminium or aluminum is a silvery white member of the boron group of chemical elements. It has the symbol Al, and its atomic number is 13. It is not soluble in water under normal circumstances....
accounts for 45 kg of the weight of the SmILE (7%), through replacement of both axles, wheel suspension and seat structure. In average cars in Europe this is 65 kg (6%) and rising. One problem with aluminium is the high energy cost of primary production. However, recycled aluminium has a much lower energy cost and identical mechanical properties.
In Germany
Germany
Germany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...
, around 10% of all cars are replaced annually by new vehicles, so if all new vehicles had the SmILE standard that would mean an annual reduction of the CO2 emissions
Greenhouse gas
A greenhouse gas is a gas in an atmosphere that absorbs and emits radiation within the thermal infrared range. This process is the fundamental cause of the greenhouse effect. The primary greenhouse gases in the Earth's atmosphere are water vapor, carbon dioxide, methane, nitrous oxide, and ozone...
of the car fleet by 5%.
A similar reduction in fuel consumption would be possible for all petrol cars, but not diesels
Diesel engine
A diesel engine is an internal combustion engine that uses the heat of compression to initiate ignition to burn the fuel, which is injected into the combustion chamber...
because they are heavier (and require heavier batteries). The Twingo was chosen because of its favourable ratio between internal space and exterior and because it is a reasonable all-round car for everyone (it is the most imported car in Germany).
Greenpeace says that ultimately, this car is not a definitive solution. Reduction of the number of cars is still necessary, also to reduce other problems, such as traffic jams, the emission of toxic substances in cities, the death toll on roads
Car accident
A traffic collision, also known as a traffic accident, motor vehicle collision, motor vehicle accident, car accident, automobile accident, Road Traffic Collision or car crash, occurs when a vehicle collides with another vehicle, pedestrian, animal, road debris, or other stationary obstruction,...
(over a million per year) and the destruction (and carving up) of nature to build roads. Alternative fuels would be a better solution, but time is pressing, so an intermediate off-the-shelf solution like the SmILE is needed.
The car was designed by the Swiss
Switzerland
Switzerland name of one of the Swiss cantons. ; ; ; or ), in its full name the Swiss Confederation , is a federal republic consisting of 26 cantons, with Bern as the seat of the federal authorities. The country is situated in Western Europe,Or Central Europe depending on the definition....
company of Wenko. For this, they received a loan of roughly 1.3 million euro
Euro
The euro is the official currency of the eurozone: 17 of the 27 member states of the European Union. It is also the currency used by the Institutions of the European Union. The eurozone consists of Austria, Belgium, Cyprus, Estonia, Finland, France, Germany, Greece, Ireland, Italy, Luxembourg,...
from Greenpeace, which they will return if the engine concept is taken over by a manufacturer for series production or profits are obtained from issuing licences.