Developing future vehicle models or innovative ideas is a risky business. Even if the computer renderings are signed off and the engineering simulations confirm a feasible solution, there is still public perception and reaction that need to be gauged. That is the reason why BMW has introduced a new step before building expensive prototypes, and they’re called “pretertypes”. According to Rainer Daude, head of BMW’S forward-looking technology office in Munich, a paper model or even a sketch is shown to a small group of people in secret before the go-ahead is given. As an example, an idea that was shelved before the prototype phase was a special trailer filled with lithium-ion batteries intended to be towed by the BMW i3 to extend its range.