From Rinspeed press: RINSPEED DESIGN, the Swiss creative source for innovative automotive concepts and fantasies, presents a very special attraction on the occasion of its 25th anniversary:
The Rinspeed Presto transforms itself in a few seconds from an under-3-meter long two-seater roadster - presto! - into a 3.7-meter long four-seater with plenty of room for the rear-seat passengers. The additional space can also be used as a pick-up bed for cargo when the rear-seat backrests are folded down.
This almost magical 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 millimeters to its full extended length of 3.74 meters. The longitudinal members run on low-friction precision rollers and disappear like a drawer in the rear of the floor pan. Despite its variable length the engineers succeeded in designing the adjustable Presto floor pan with the torsional rigidity necessary for a roadster. To ensure absolute operational safety the extension mechanism also features self-locking safety latches.
A four-cylinder, 1.7-liter common-rail turbo diesel engine in dual-fuel configuration, based on a Mercedes-Benz engine, provides future-oriented and highly environmentally friendly propulsion. The engine runs on a mixture of natural gas and Diesel fuel at a 40 to 60 ratio. Natural gas is a very clean-burning fuel, which consists almost entirely of methane 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 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 level of reliability as the production car.
This technology has enormous potential for reducing exhaust emissions and fuel consumption. Emissions of nitrous oxides and carbon dioxide can be lowered by as much as 10 percent compared to the already extraordinary low level of the production engine. Particulate matter emissions can be lowered by up to 40 percent. With emissions this low the dual-fuel engine easily meets all existing and currently planned emission limits. Fuel consumption can be improved by up to 10 percent compared to a production engine.
The dual-fuel engine is compelling proof that environmental protection and driving fun can go hand-in-hand: The four-valve engine develops maximum power output of 120 hp / 88 kW at 4’200 rpm, and produces maximum torque of 224 Nm at just 1’600 rpm. Performance is boosted accordingly: The 865-kg quick-change artist accelerates from 0 to 100 km/h in approximately 10.5 seconds and reaches a top speed of approximately 180 km/h.