The Rinspeed Presto is a

concept car A concept car (also known as a concept vehicle, show vehicle or prototype) is a car made to showcase new styling and/or new technology. They are often exhibited at motor shows to gauge customer reaction to new and radical designs which may or ...

from the Swiss company

Rinspeed Rinspeed Inc. is a Swiss concept car builder and mobility visionary. Since 1991, they have also designed exotic concepts and special vehicles for the CES in Las Vegas, the Geneva Motor Show and other car shows each year, but do not enter into pro ...

, unveiled in 2002. At the touch of a button, it would expand it from a 2.7 metre, two-seat cabrio to a 3.6 metre, four-seater. It has a Pre-Peg Composite plastic body and runs on

natural gas Natural gas (also called fossil gas or simply gas) is a naturally occurring mixture of gaseous hydrocarbons consisting primarily of methane in addition to various smaller amounts of other higher alkanes. Low levels of trace gases like carbo ...

. The transformation is made possible by a centrally located electric motor, which stretches the vehicle with the help of two mechanical screw-and-nut gears by exactly 746 millimetres to its full extended length of 3.74 metres. The longitudinal members run on low-friction precision rollers and disappear like a drawer in the rear of the

floor pan The floorpan is a large sheet metal stamping that often incorporates several smaller welded stampings to form the floor of a large vehicle and the position of its external and structural panels. In the case of monocoque designs, the floorpan i ...

. Despite its variable length the engineers succeeded in designing the adjustable floor pan with the

torsional In the field of solid mechanics, torsion is the twisting of an object due to an applied torque. Torsion is expressed in either the pascal (Pa), an SI unit for newtons per square metre, or in pounds per square inch (psi) while torque is expressed ...

rigidity necessary for a roadster. To ensure absolute operational safety the extension mechanism also features self-locking safety latches. The car lacks a roof and doors. Conversion: A four-cylinder, 1.7-litre common-rail turbo

diesel engine The diesel engine, named after Rudolf Diesel, is an internal combustion engine in which ignition of the fuel is caused by the elevated temperature of the air in the cylinder due to mechanical compression; thus, the diesel engine is a so-ca ...

in dual-fuel configuration, based on a

Mercedes-Benz Mercedes-Benz (), commonly referred to as Mercedes and sometimes as Benz, is a German luxury and commercial vehicle automotive brand established in 1926. Mercedes-Benz AG (a Mercedes-Benz Group subsidiary established in 2019) is headquartere ...

, runs on a mixture of natural gas and diesel fuel at a 40/60 ratio. Natural gas is a very clean-burning fuel, which consists almost entirely of

methane Methane ( , ) is a chemical compound with the chemical formula (one carbon atom bonded to four hydrogen atoms). It is a group-14 hydride, the simplest alkane, and the main constituent of natural gas. The relative abundance of methane on Ea ...

with sulfur content near zero. However, since a diesel engine has no spark plug to act as an ignition source, operation on natural gas alone is technically impossible. The operating principle of the dual-fuel engine is simple: Natural gas is injected into the intake air of the engine. Just like in the production engine the diesel fuel is injected into the

combustion chamber A combustion chamber is part of an internal combustion engine in which the fuel/air mix is burned. For steam engines, the term has also been used for an extension of the firebox which is used to allow a more complete combustion process. Intern ...

where it ignites a mixture of natural gas and air rather than just plain air. To configure the turbocharged in-line engine for dual-fuel operation, a number of modifications are required, including installation of a tank for the natural gas and a gas-injection system. At the heart of the modifications is a reprogrammed engine management system. Should the system malfunction it reverts to the standard diesel mapped ignition, thus offering the same reliability as the production car.

External links

Rinspeed Presto on the Rinspeed site
Concept cars Sports cars {{Modern-auto-stub Rinspeed vehicles