- 13 kg weight reduction compared to glass
- 100 times the impact resistance of glass
- 15 additional kilometers in extended range
On October 20, 2014, BMW, Daimler, scientists of the Technical University of Munich and a consortium of industry participants showcased the lightweight electric concept vehicle Visio.M. The car’s windows feature an all-plastic design made from polycarbonate (PC) which helps to keep the overall vehicle weight to a minimum, while also delivering improved acceleration, vehicle handling and security.
PC windows reduce weight by over 13kg
The use of Lexan polycarbonate material of Sabic reduces the weight by over 13 kilograms compared to conventional glass for the car’s windows and extends the vehicle’s driving range by up to two kilometers for a single battery charge. PC’s superior insulating properties reduce demands on the car’s heating and air conditioning (HVAC) system and make possible up to 15 additional kilometers in extended range.
Improved vehicle handling due to lower center of gravity
The lighter weight of the PC windows contributes to a lower center of gravity, which tends to have a favorable effect on the vehicle’s handling and stability. The reduced weight also means that the vehicle requires less energy to accelerate at a quicker rate. In terms of vehicle security, Lexan resin has up to 100 times the impact resistance of glass. As a result, the concept car’s windows can reduce risk from theft, an important feature for urban cars.
Advanced plasma coating for abrasion resistant moving windows
The Visio.M concept features PC-based front side moving windows, rear quarter windows and a backlite, all produced with Lexan resin and coating technologies that enable fulfillment of regulatory requirements, including those for glazing located ahead of the B-pillars, which are required for driver visibility. The moving windows use SABIC’s Exatec E900 coating, an advanced plasma coating that meets abrasion resistance requirements and enhances weatherability. Although not required to homologate the backlite, the same plasma coating would also enhance the durability of this window, which includes a wiper. The Visio.M windscreen is also produced with Lexan resin, recognizing the potential for changes in European legislation which would allow PC to be used in this window application. Current legislation permits PC use in all automotive glazing applications, except the windscreen.
Use of PC enables part consolidation
The Visio.M windows were designed to use PC or glass for testing and comparison purposes. SABIC says that if the windows had been designed for PC alone, additional energy efficiency gains could have been achieved. This is because of PC’s greater shape flexibility compared to glass, which allows for curvatures, 3D styling and aerodynamic features that can minimize drag. The greater design freedom from the use of PC can also enable part consolidation and integration possibilities with traditionally separate components such as pillars, mirrors, cameras, rear lighting and spoilers.
The Visio.M concept EV features a 15kW electric motor and a weight of 450 kilograms (without battery), standard requirements that allow the vehicle to meet the new European regulatory category L7e (heavy quadricycles).
The unveiling of this concept vehicle is the result of over two-and-a-half years of research and development as part of the Visio.M (Visionary Mobility) project. This joint effort, funded by the German Federal Ministry of Education and Research (BMBF), has focused on producing an exceptionally light electric car that is efficient, safe and mass-marketable. The consortium, in addition to BMW, Daimler and TUM, includes Autoliv, Germany’s Federal Highway Research Institute (BASt), Continental, E.ON, Finepower, HYVE, IAV, InnoZ, Intermap Technologies, LION Smart, Neumayer Tekfor, Siemens, Texas Instruments and TÜV SÜD.