Rainer Rump is the Project Manager who oversaw the creation of the BMW i8 Roadster. Therefore, the marketing people over in Munich decided that he would be the perfect person to explain the technical side of the drop top.
Apart from the obvious spec sheet anyone can get a hold of, the footage below also throws in a couple of interesting tidbits. For example, the textile roof can be retracted in 15 seconds at speeds up to 50 km/h (31 mph) which is more than any other BMW today. Furthermore, once the roof has been pulled back, the rear window will automatically move into the so-called comfort position which is the optimum position in terms of turbulence and aeroacoustics.
Of course, that position can be overridden by using the manual switch located on the windshield, just above the rearview mirror. Rainer also goes over some of the hiccups he and the team he led had to overcome during the car’s development. Some of the testing was already done for the Coupe model which has been around for years but when stripping the roof off of a car, certain unexpected issues can pop up.
In the footage below we get to learn about the ‘sprazzeln’ phenomenon which would occur speeds around 60 km/h. This was apparently a sound caused by the wind getting caught in the grille of the midrange speaker and tweeter located next to the driver. Therefore, the team had to get creative in order to solve this problem. The solution is quite interesting and simple though but we won’t ruin the surprise of letting you find it out on your own by watching the video below.